The experienced French central defender has impressed since returning to the fold at Chelsea a fortnight ago.
It’s been a stop-start season for William having been laid low by calf trouble, but he’s back and ready to play his part in the key final weeks of the campaign.
“I think the confidence is back after the draw at Chelsea, the win against Bolton and the win against Swansea,” said William.
“Our target is to finish third and every game is a final for us.
"We have to be strong if we want to finish third, we have to play every game at 100 per cent. We’ll give everything.”
William was particularly impressed with Emmanuel Adebayor’s performance in Sunday’s 3-1 win against Swansea.
“Ade runs everywhere, he can keep the ball, he has big quality,” added William. “He scored two goals against Swansea and was very good for us.
“It was an important win because it meant we came back on Arsenal.”