MICHAEL Appleton has warned his back four cannot afford to switch off for a moment against Millwall’s dangerous strike partnership tomorrow.

Steve Morison and Lee Gregory are expected to lead the line for the Lions at the Kassam Stadium.

The experienced pair have netted almost 250 goals between them during their careers and have 14 already in a campaign where Millwall have struggled to recapture the form which took them to the Sky Bet League One play-off final in May.

Gregory scored at United during the Johnstone’s Paint Trophy area final last season, which Appleton’s side won 2-1 on aggregate.

And the U’s head coach stressed the front two had the ability to change the game in an instant if his defenders are not careful.

He said: “They’ve not made the start they would have liked after finishing last season strongly to get into the play-offs.

“They are still a very difficult side to play against – they get the ball into the strikers very early.

“The two they have in Morison and Gregory are as good as any in the division, so it’s something we have to be mindful of.

“We could play really well and put a top performance in, and then one lapse in concentration on a long ball and a flick-on could cost us.”