Derk Boerrigter put Frank de Boer's side in front late in the first half and Kolbeinn Sigthorsson sealed the win with a second goal in the 80th minute.
Victory kept the Amsterdammers six points clear of AZ Alkmaar and Feyenoord, who both recorded 2-1 wins, with three matches to go.
AZ saw off lowly VVV-Venlo, Jozy Altidore's header settling the contest in the 65th minute.
Brett Holman had put AZ in front just after the break only for Quin Kruijsen to level.
Third-placed Feyenoord claimed a 2-1 success at ADO Den Haag.
Ruben Schaken put the visitors in front just after the restart and Guyon Fernandez doubled the lead with 19 minutes left.
Lex Immers pulled one back for ADO from the penalty spot in the 90th minute, but the visitors held on to keep their slim title hopes alive.
PSV Eindhoven are a point further back in fifth after they came from behind to beat NEC Nijmegen, also 2-1.
Jan Vennegoor of Hesselink scored the winner
two minutes from time after Jetro Willems' 68th-minute leveller cancelled out Navarone Foor's early opener.
Ajax has released their away soccer jersey for the 2013/14 season. Get in the Gear.
The new PUMA evoSPEED 1.2 FG. A great new soccer cleat with classic look and first time for PUMA to be on the cleat.
The adidas Nitrocharge is the most talked about new cleat in years. It was released on May 15 and will take your pitch by storm.
The push for more color on their cleats, adidas has added the infrared colorway to the adiZero f50 Line.
adidas has added some color to the Predator line with this new colorway. Released on May 17. Be the first to own a pair.
Bayern Munich are kings of Germany and hope to be crowned kings of Europe at Wembley later this month!
The Liverpool 2013/14 soccer jersey is available for pre-order. The Reds are eager to compete for silver next season.
Chelsea won the Europa League on Wednesday. The Blues defeated Benfica 2-1 on injury time goal from Ivanovic.
Borussia Dortmund hears Wembley Calling and are headed to London for the Champions League final.
One of the top soccer cleats for control the Nike CTR360 will not let you down on the field in tight spaces.