A goal and assist from Toyosi Olusanya continued Aberdeen's improvement under Stephen Robinson as they defeated Dundee United at Pittodrie to stretch their unbeaten Scottish Premiership run to four games.

Olusanya, who had failed to score in his first 15 games and was starting to come in for criticism, ended up as the decisive player by playing his part in all the big moments of the game.

Firstly, he fashioned the opening goal with a trademark run forward. The striker managed to slow down and lay the ball to Stuart Armstrong, who calmly stroked the ball into the bottom corner to put Aberdeen deservedly in front.

Olusanya was also key in the final six minutes after Aberdeen had held off a United fightback.

First the forward's speed forced Emmanuel Agyei to trip him for the second time, resulting in another yellow and sending off for the United midfielder.

Then he was lurking to side-foot his first Aberdeen goal high into the net and seal victory after Lyall Cameron's shot was initially saved by goalkeeper Dave Richards.

Up until the sending off United were pushing for an equaliser in response to a poor first half.

Zac Sapsford finished sharply in the box only for the player who laid the ball to him, Julius Eskesen, to be flagged offside.

Then Ivan Dolcek was convinced he had been felled by Afeez Aremu when only 10 yards from goal, only for referee Duncan Nicolson to wave away his pleas for a penalty, a decision affirmed by the video assistant referee.

Overall, though, United were blunt in attack and slipped to a second consecutive defeat, with Aberdeen now just three points behind them with two games left as both seek to end the season as the best side in the bottom half.

Some Aberdeen fans were sceptical when manager Robinson said this week he is keen to extend Olusanya's stay beyond his loan from Houston Dynamo.

His glaring miss when clean through against Livingston last week was seen as the latest proof the former St Mirren player does not have the composure required to play up front for Aberdeen.

It had been 15 games without a goal, albeit in an Aberdeen side that does not create lots of chances.

Against United there was plenty of wastefulness. He had a free header inside the box which he could not guide anywhere near the target, and a sclaff wide from Mitchel Frame's cut back.

But his searing pace and fantastic attitude unsettles centre-backs to the extent that he always manages to find himself in good attacking positions and cause major problems.

His goal at the ends was just reward for his overall performance, and he provides something different to Aberdeen's attack, which has been poor all season.

Robinson got plenty out of him at St Mirren, and will hope to keep doing the same with Aberdeen.

The last two games have been poor from United, after their rousing derby win over Dundee at Tannadice.

It is understandable given they have had very little to play for since the split, and losses to Kilmarnock and Aberdeen have continued to show up well-known issues.

Too many times this season they have conceded poor goals, and again the slackness that allowed Olusanya in for the opening goal was costly.

Up the other end they have become slightly too reliant on set-pieces, having scored the third most in the league, with creativity lacking in open play in the absence of the injured forward Amar Fatah and his nine goals.

A massive squad rebuild to cut the wage bill and lower the average age of the squad has been successful in the main despite a bottom-half finish.

But phase two has to be adding more experience and quality if they want to kick on for next season.

Aberdeen manager Stephen Robinson: "The first job done that we set out to do was to steady the ship and make sure we are well away from the relegation play-off spot which looked like somewhere we could be heading.

"Credit to the players, they've bought into everything. We've tried to get them more solid and more organised and that's three clean sheets in a row."

Dundee United manager Jim Goodwin: "The first 45 minutes was really, really poor. I don't think there was a great deal of quality from either team in the opening period.

"We got done with one ball over the top for Toyosi Olusanya, which is something we analysed all week. We spoke about it and worked on it in training.

"At 1-0, we are always in the game. The second-half was slightly better but nowhere near good enough for the quality of players that we have. To not have scored in the last two games is not acceptable."

Aberdeen host St Mirren on Tuesday night in their penultimate league game (19:45) while Dundee United host Livingston at the same time.