Manchester United's Wayne Rooney wary of improved Liverpool

Manchester United striker Wayne Rooney
Rooney has won four Premier League titles with Manchester United

Manchester United striker Wayne Rooney says Liverpool "will challenge" for the Premier League title in the new season.

Liverpool, who finished sixth last term, have signed midfield trio Jordan Henderson, Charlie Adam and Stewart Downing during the summer.

"They have made some really good signings," said Rooney.

"I am sure they will be fighting harder than they ever have done to be up there. They will think they have a chance of winning the title."

The former Everton man continued: "The main threat is going to be from Chelsea, Liverpool, Arsenal and Manchester City.

"One of them, plus us, will be fighting for the title."

Rooney will be aiming to collect a fifth Premier League winners' medal this season with United, but he wants to kick-off the season with a victory over FA Cup winners Manchester City in the Community Shield at Wembley on 7 August.

"When you play at a club like Manchester United, the goal is to win all the competitions," said the England international.

"It is true our priority is to keep our Premier League title, but we won't ignore any competition.

"We want to win everything, starting with the Community Shield. There is nothing better than a derby to start the season."

The 25-year-old also said United's summer signings have made him feel like a relative veteran at the club.

United have bought 20-year-old goalkeeper David De Gea and teenage defender Phil Jones from Blackburn, as well as Ashley Young from Aston Villa.

"There have been a lot of changes this summer and when you look around the dressing room now, suddenly it's a lot younger place.

"The manager is bringing in players who have not won a league title before and they all have that hunger and desire to want to win trophies."

Rooney's return of 16 goals in all competitions last season represented his lowest tally since the 2003/04 campaign, his last at Everton before moving to Old Trafford.

He added: "I don't set targets for myself but it would be nice if I can get through the season injury free. It's always a big thing to get your pre-season under your belt because that is the main bulk of the work you get to do.

"We have trained very hard this week and we are looking forward to all the games."

United continue their pre-seaon tour of the United States against Chicago Fire on Saturday, before they face an MLS All-Stars team that will include David Beckham and Thierry Henry on 27 July.