Feyenoord 3-1 PSV
The home side deservedly took the lead just before the half hour. A superb Diego Biseswar cross from the right picked out Wijnaldum, who timed his run to perfection and headed the ball past Isaksson, sparking cheers from a fervent home support in De Kuip.
Fred Rutten introduced Ola Toivonen at the break as PSV sought an equalizer but things went from bad to worse when Orlando Engelaar was handed a straight red card on 54 minutes after a clumsy two footed lunge on Luc Castaignos.
Ten-man PSV then leveled the game on the hour with a wonderful finish. Jeremain Lens raced clear of the Feyenoord defense and unleashed a shot that struck the post before rebounding to Toivonen, who coolly curled the ball into the net from just outside the box.
Feyenoord restored its lead three minutes later with a goal that was almost a carbon copy of the opener. Wijnaldum headed another pinpoint right-wing cross from Biseswar past Isaksson for his 13th goal of the campaign.
The icing on the cake for the home side came on 78 minutes through Castaignos, who was handily placed inside the penalty area to slide home Kamohelo Mokotjo's cutback from the right.
PSV drops to third behind Ajax and they go into next week's home game with Vitesse three points off leaders Twente with two matches to play.
Ajax 4-1 Excelsior
It was however Ajax which went ahead after 13 minutes with a superb finish from youngster Lorenzo Ebecilio. His first attempt was blocked but at the second time of asking, he produced a wonderful shot into the bottom corner for just his second senior goal.
The visitors spurned a magnificent opportunity to equalize in the 28th minute when their leading scorer Guyon Fernandez disappointingly headed wide before he left the field six minutes later.
Excelsior's 54th minute equalizer came unsurprisingly from a set-piece. Daan Bovenberg headed Ryan Koolwijk's free-kick into the corner to net his second goal in as many games against Ajax this season.
Geert Arend Roorda's miss on 65 minutes proved to be costly as Ajax restored its advantage six minutes later. Gregory van der Wiel timed his run into the penalty box to perfection before squaring the ball to Eriksen, who bundled the ball over the line.
The three points were sealed for Ajax on the counterattack with 11 minutes remaining. Miralem Sulejmani kept his cool to scoop the ball over Nayib Lagouireh for Ebecilio, who in trying to gather the ball, took it past a helpless Pellatz. Siem De Jong then added a magnificent fourth in stoppage time with an acrobatic overhead kick.
Ajax now move above PSV into second, one point behind Twente. Next week, Frank De Boer's men face a potentially tricky trip to Friesland to meet Heerenveen.
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