Edwin van der Sar has warned Manchester United they face more European pain if they underestimate Ajax.

United are expected to see off Ajax over two legs. But Van der Sar reckons the Old Trafford giants could be stunned again if they take Ajax too lightly.

Ex-goalkeeper Van der Sar said: "It's very painful to see Manchester United in the Champions League.

"You automatically associate Manchester United with the Champions League - it's where they belong.

"But the European campaign this season proves that Manchester United are not unbeatable. They may beat Ajax but if FC Basel can defeat Manchester UnitedAjax also have a chance.

"They will need to seize any luck. Otherwise Ajax will be punished. That does not mean that Ajax has no chance."