Vidic accepts the team must tighten up at the back.
"We always know that on set-pieces they are a tough team to play against and eventually they scored two against us from crosses," the centre-back said.
"They scored from the second ball which we should look at again, and we are definitely a bit disappointed. It is something to talk about.
"We have the height in the team, we should deal better with that, but most important is that we managed to stay in the game."