The big derby clash felt like a significant one for several reasons. For Galatasaray, it was their toughest game remaining this season, and a victory would see them take a major step towards a third successive title.
For Besiktas, they would have the chance to end Galatasaray's uneaten league season, and also claim a serious statement victory under Ole Gunnar Solskjaer - a victory that would see them improve their chances of a top three finish.
Besiktas started the game quickly and on the front foot, and took the lead courtesy of Rafa Silva. The Portuguese player was given acres of space to charge down the left wing, before some really sloppy defending from Davinson Sanchez allowed Silva to slot home at the near post.
The way things were going, the home side were looking likely to score another. However, Przemyslaw Frankowski was controversially sent off for Galatasaray after being deemed to deny a clear goalscoring opportunity, despite the fact that the ball was heading away from goal and there were two covering defenders.
This actually played into Galatasaray's hands, however. Besiktas have lost their last two games against teams who were playing with nine and 10 men. They evidently struggle to break teams down who are setting up more defensively, something Galatasaray had very clearly not been doing.
But once they were reduced to 10 men, Besiktas lost their momentum and were unable to attack with the same speed and ferocity they previously were. This allowed Galatasaray back into the game, with Lucas Torreira scoring a wondergoal from around 30 yards out on the cusp of half time to level proceedings.
The second half was a much tamer and lower-quality contest. Neither team were able to get too much going until Gedson Fernandes stepped up.
The midfielder pounced on a scuffed Joao Mario shot and some more weak defending from Galatasaray to score the goal that would seal a 2-1 victory for Besiktas.
Their forward, Semih Kilicsoy, was sent off in the dying minutes for what can only be described as one of the softest red cards you are ever likely to see. Bizarrely, the referee hadn't even given a card on the field, and the overseas officials in the VAR booth decided it should be a sending off. Awful decision.
So what does this mean?
It feels like a big moment for Besiktas. Inflicting a first loss on Galatasaray this season will have given them immense satisfaction and confidence and will surely unite fans behind their team and manager following a tough campaign.
The team is still flawed, and they need to be busy in the transfer window, but a result like this is huge. Third-place Samsunspor also suffered a surprise defeat on the weekend, so Besiktas are now just four points off them with a game in hand.
Silva and Fernandes are certainly their main stars and continue to produce week after week. The Portuguese duo are high-quality players and will be massive assets to Besiktas next season when they revamp their team.
Galatasaray, on the other hand, will be more concerned about the manner of the defeat rather than the actual loss itself.
Realistically, they were going to lose a game at some point this season. But it is the fact that there has been such a lack of a plan or any sort of style in recent months, and players are really starting to look lost out on the pitch.
A six-point lead - albeit with a game in hand - and a superior head-to-head record with Fenerbahce means they are still in control of the title race with just eight games to go.
But Galatasaray have just two wins in their last seven in all competitions, and key players like Gabriel Sara are out of form, while new signings Frankowski and Alvaro Morata are struggling in this system.
Manager Okan Buruk is coming under serious pressure from fans, and he needs to find a way to get his team playing better. Luckily for him, they visit Fenerbahce this Wednesday in the Turkish Cup!
Fenerbahce ease to win
The day before the game between Besiktas and Galatasaray, Fenerbahce returned to action away at lowly Bodrumspor.
Interestingly, Bodrum had been in some really good form, helping them make a move towards safety. They hadn't conceded a goal in seven games in all competition, which is a truly remarkable statistic.
But against Fenerbahce, it was just a step too far, as Jose Mourinho's side coasted to a straightforward 4-2 win.
Oguz Aydin, Milan Skriniar, Sebastian Szymanski and Anderson Talisca all got on the scoresheet, with the former standing out yet again.
Oguz has been a major success story for Fenerbahce. The 24-year-old winger was signed from Alanyspor in the summer and has consistently put in top performances to make himself a key member of the team.
He was rewarded for his fine season with two starts for Turkey during the international break, in which he shone, providing three assists across the two Nations League games against Hungary. As a result, he received glowing praise, with reports in Turkey now claiming several European clubs are interested in the player.
Importantly now for Fener, Galatasaray do not play this weekend. They will have the chance to narrow the gap to their rivals down to three points. However, a very tricky match at home to Trabzonspor awaits, but they simply have no room for error at this stage in the season.
Highlight of the week
Adolfo Gaich came off the bench to snatch a late 2-1 win for Antalyaspor against Alanyaspor, but he received a huge helping hand from goalkeeper Ertugrul Taskiran, who made this shocking error.
Team of the Week
Rey Manaj is Flashscore's Player of the Week after the Sivasspor striker scored two goals and provided two assists in his side's 5-1 win against Adana Demirspor.
Besiktas pair Silva and Fernandes also make the team after their impressive displays, while Skriniar finds his place in the heart of defence.