Derek McInnes shook things up for the Dons after the defeat to Rijeka on Thursday with Zak Vyner coming in for Shay Logan to make his debut. Scott Wright started the game in place of Jon Gallagher, Connor McLennan replacing Niall McGinn, those three Rijeka starters dropping to the bench. Curtis Main came in for his first senior start in place of the absent Sam Cosgrove. The hosts made two changes from their 1-0 defeat at Hibs, Waters and Obika in for MacPherson and Mullen.
With the St Mirren pitch having taken a pounding from the rain, which continued to pour down, conditions were awkward with patches of standing water on the surface.
Four minutes in, Main did well to earn the Dons a corner on the left, but St Mirren cleared their lines in comfort. Five minutes later, the Aberdeen wall did its job to fend off a fierce free-kick from Durmus, then St Mirren repelled two Dons corners in quick succession in a very scrappy opening.
The hosts finally put a move together in the 13th minute, a break down their right from Magennis, getting him into a good position to play a precise square ball into the run of Durmus who produced a neat first time finish just inside Joe Lewis' post from just inside the box to give St Mirren the lead.
Aberdeen responded in the 16th minute, a Greg Leigh throw reaching Main who turned sharply but turned his shot behind from a tight angle. Durmus could have had his second a minute later, heading over when unopposed on the penalty spot after a fine cross from Waters, a let off for the Dons who were struggling to get a foothold in the game amid the torrential rain.
Another golden chance went begging for St Mirren when, after McLoughlin stood the ball up to the back post, Mackenzie headed over from six yards in the 21st minute, then a minute later, Scott McKenna had to find a fine last ditch tackle to deny Obika who was in on goal.
Good feet from Connor McLennan won the Dons a free-kick 30 yards out on the half hour mark, Aberdeen eventually working the ball into a shooting space for Ryan Hedges, his 20 yarder going straight down the goalkeeper's throat.
The Dons were gradually improving and another free-kick came their way in the 37th minute, some 35 yards out. Lewis Ferguson took a pot shot at goal but the ball flashed well over the bar.
Another corner was won down the left a minute later, McLoughlin hacking clear in the six yard box from a teasing Wright delivery in, but still the visitors could not fashion a real opening.
Yet another corner came from the same side in the 43rd minute, half cleared to McLennan whose thumping drive was blocked away for another which again came to nothing. Six first half corners without creating a semblance of a chance was frustrating fare.
St Mirren almost finished the half on a high, a quick break ending with an overhead kick from Durmus that was well handled by Lewis, bringing the first 45 minutes to an end.
No changes to either side - or to the weather - at the start of the second half, the rain still hosing down in Paisley.
A period of sustained possession opened the half for Aberdeen, culminating in Main firing not far over from the edge of the box in the 48th minute but again, the game struggled to find any pattern early on.
Some 54 minutes in though and the Dons came close, Ferguson up well to head Vyner's penetrating cross goalwards, Hladky doing well to tip it over, a fine save. By now, the Dons were dominating possession, but good organisation from the hosts meant there were precious few gaps.
Controversy flared in the 57th minute when Main felt Hladky had lost possession of the ball on the touchline with just one hand on it. The striker flicked it away from him and tucked the ball away but the goal was not given.
Just short of the hour, Flynn tangled with Ferguson to give the Dons another free-kick on the corner of the box, Hedges' skimming ball in fisted away by the goalkeeper.
More controversy in the 61st minute when Hedges' ball in was clearly handled by Flynn, the referee ignoring the penalty appeals and booking Vyner for dissent - if he'd seen the replay, he'd have understood the full-back's frustration for it was an obvious penalty kick.
Derek McInnes made a double change on 62 minutes as on came Niall McGinn and Jon Gallagher for McLennan and Wright as Aberdeen looked to capitalise on this building momentum. Eight minutes later, Jim Goodwin made his first change, McAllister on for goalscorer Durmus.
Goodwin should have had himself another goalscorer almost immediately, a teasing cross on the run from full-back McGinn finding Andreu just six yards out but somehow, he shaped his header wide of goal when he should have at least hit the target. St Mirren then made a second change on 75 minutes, Obika replaced by Mullen.
Aberdeen almost unlocked the door on 76 minutes, McGinn's fierce cross blocked at the near post by a defender. It nearly dropped for Main but Hladky was quick off his line to smother. Ojo collected a yellow for a rugby tackle on Foley in the 78th minute as the Dons began to lose a little patience. The hosts had the next chance though, good work from Magennis working a shooting chance that Andy Considine had to block behind.
They had another chance to seal it in the 82nd minute, McAllister picking up a loose pass from McKenna before driving forward 40 yards and firing over from the edge of the box.
James Wilson was Aberdeen's final change in the 87th minute and he quickly created a shooting chance for Hedges but he didn't catch it how he wanted and Hladky had another comfortable save to make. Almost immediately, Breadner replaced Andreu in the hosts' final substitution.
A ridiculous challenge on Ferguson saw Mullen into the book and from the resulting free-kick, the Dons finally worked an opening, Considine's clipped cross finding McGinn unmarked at the back post but from a tight angle, his shot smashed against the post and away behind.
The Dons laid siege to the St Mirren goal in the four minutes of added time, Ojo drilling a 25 yarder just past the post but for all their dominance of possession, Aberdeen could not find a way through and came home defeated.
"But it did not come and sometimes that happens.
"I think it is a penalty with last years rules. I think it is even more of a penalty with the rules that we were told about at the referee's meeting two weeks ago.
"The referee has given me his take on it. Obviously, it is different from mine and different from what I think we were told at the meeting. I think there is enough distance there for it to be a clear handball and therefore a penalty.
"It was not just about that.
"St Mirren set up exactly how we thought. Similar to how they set up last week when they were away from home. I thought they were very good on the counter attack last week at Easter Road and I thought it was a very good performance from them. Prior to the game, we thought they maybe deserved something from last week.
"So we anticipated the team and how they would play when the teamsheet came in.
"It was our job to try and play with a bit more speed. We tried to bring more speed into the team with Scott and Connor and also Ryan, who all played behind Curtis. But we never really got as much of that pace into the game as we would have liked.
"Everything was a bit safe and a bit pedantic in the first half in terms of our build up.
"St Mirren score a good goal from their point of view, counter attacking goal and a nice finish. They then have something to hold onto.
"I think Jim set them up well, they are very competitive bunch of boys and the onus was on us at half time. I thought the way we approached the second half was far more what was needed in terms of more aggression, more speed; asking the question more.
"Unfortunately we never quite managed to get an equaliser. The penalty decision that should have been would have helped but it did not come and we are very disappointed we haven't taken something from a game that I thought we deserved.
"There was one part of the pitch in front of the dugouts which was a concern for me during the warm up. But I don't think it was quite enough for the game to be stopped. It was not perfect but we all wanted the game on. The pitch was good enough for the game to go ahead.
"Sam had a tightness in his hamstring yesterday. He reported with it when he started doing his work yesterday morning in the warm-up. We tried to give him every chance but he just felt it was becoming more of an issue and we decided not to bring him with us so he could stay back and get some treatment in Aberdeen. He will get a scan tomorrow. He will be touch and go for Thursday. "Any team would miss someone in Sam's form and we are hopeful he will still make it but at this stage it is not clear yet.
"We got into enough good areas today. The onus is on everyone to try and score, even from set plays. Again my best players today were Considine and McKenna, as they were on Thursday. I thought when called upon to defend they were very good.
"I thought first half we could have done far more with the possession we had. The stats will show you how much possession we had in the final third, but the only stat that matters is goals scored and unfortunately for us St Mirren got their goal and we did not quite manage to do enough.
"I thought in terms of the impetuous and aggression in the second half it was far better. The players were clearly doing everything they could to try and get something from the game. I thought we probably deserved something from the game but ultimately we never and we leave disappointed.
"When you go through in Europe and you go through the rounds and you come up against a tougher opponent, and Rijeka are a good side. They have been one of the top sides in Croatia for a while now and they have got a strong European pedigree. I thought we were a bit unfortunate to leave with a 2-0 defeat but again, similar to today, I thought my best players were defenders.
"This Thursday we are going to have to get a bit more of an attacking threat going. At Pittodrie this season we have had that. We have scored umpteen goals, we have been very good in the three home games up until now. It is going to take that and a bit more to overcome this team because they are a capable side - battle hardened and experienced, athletic and have players who can hurt you, as we saw with the second goal.
"But we know with Pittodrie busy and with Pittodrie lively, an early goal and we can certainly ask the question of them and that is certainly the intention. The first goal is clearly going to be pivotal in the nights work."