Shaun Williams' stoppage-time header was enough to send Millwall through to second round of the Johnstone's Paint Trophy as they recorded a narrow 1-0 win over Peterborough.

Williams flashed a shot from outside of the box just wide of the post after 15 minutes and also saw a 20-yard free-kick fly inches past Ben Alnwick's post.

However, it was Peterborough who came closest to breaking the deadlock when - three minutes before the break - Kyle Vassell picked out the unmarked Harry Beautyman, only for the substitute to drill his effort behind.

Ed Upson was denied by Alnwick early in the second half, while opposite number Jordan Archer did well to thwart Conor Washington moments later and then tipped over a Christopher Forrester attempt.

Williams came close again on the hour with a dipping long-range shot which flew agonisingly over the bar and Ben Thompson was unlucky to see his effort go behind.

Upson showed real skill to get through the visiting defence and only a superb piece of Alnwick keeping prevented Millwall breaking the deadlock on 72 minutes.

But with penalties seemingly looming, Carlos Edwards' inviting delivery was headed home by Williams to give Millwall a much-needed first home win of the season.