London, Dec 9 : Manchester United skipper Nemanja Vidic has warned Wayne Rooney and his fellow strikers they must sharpen up against Arsenal and Chelsea.

Rooney, who is still searching for his first club goal from open play in nine months, was not able to score despite an excellent showing in Tuesday's 1-1 draw against Valencia.

Manchetser United face Arsenal at Old Trafford on Monday before travelling to take on champions Chelsea at Stamford Bridge on Sunday week.

Vidic said: "Our form is getting better. We had a few good chances against Valencia and played some good football. We didn't take all the chances and in games like the ones against Arsenal and Chelsea, you have to keep your focus."

"There aren't going to be so many chances. Everything you have, you have to take if you want to win. So I hope we will be in good shape and all our players will be fit, because we are looking forward to the game," The Sun quoted him, as saying.

"We have to be pleased with how many chances we made against Valencia but we didn't take them. In the end it was a bit of a nervous game. In the last 10 minutes we had to make sure we didn't concede a goal so we could achieve what we wanted to achieve - to be first," he said.

Vidic has labelled the clash with current leaders Arsenal as United's biggest of the season so far.

He said: "We would have a big advantage if we won those two games and we'd be in a great position. I think it's the biggest game for us so far this season, especially when you're getting to this stage in December."
(ANI)