By Mark Lamport-Stokes

OAKMONT, Pennsylvania (Reuters) - Former champion Justin Rose heads into this week's U.S. Open at Oakmont Country Club with limited preparation behind him after "a race against the clock" to be fit for the year's second major championship.

The 35-year-old Englishman has not competed since tying for 19th at last month's Players Championship in Florida, having withdrawn from the European Tour's PGA Championship at Wentworth two weeks later due to a back injury.

"I've done everything humanly possible to be here from a recovery point of view, from a fitness point of view, from a practice point of view," Rose told reporters at Oakmont on Tuesday. "It's been a race against the clock really.

"There's no doubt my practice schedule has been on the light side, limiting the number of balls I've been hitting. I only started hitting the driver two or three days ago, so it's definitely been a tight timetable.

"But I'm confident I've done a lot of the really hard work, especially in the gym, especially re-engaging all the strength around the core, and all that stuff is going to support me this week."

Rose, who won his first major title by two shots in the 2013 U.S. Open at Merion, felt that coming into this week after a break from competition could benefit him as he prepares to tackle a venue regarded as one of the toughest anywhere.

"This golf course is going to require a huge amount of patience," Rose said of the hilly, par-70 layout at Oakmont which has very few flat lies and is renowned for its lightning-fast, undulating greens.

"Having that quiet time to sit back and assess my game, assess the challenge this week and coming in with a freshness could be an advantage come the end of the week."

Rose will this week be competing in his 11th U.S. Open and he hopes to draw on memories from his tie for 10th when the championship was last held at Oakmont in 2007.

"I think I was in and around the lead for the most part from Thursday through Sunday ... in the top 10 all week," he recalled. "Knowing I've done it, knowing I've played the course to a decent level, obviously helps.

"Can I really remember exactly how the course played and what my game plan was? Not really. I think that my game has changed and evolved over the years, so it's good to sort of see it through a fresh pair of eyes this week.

"Just having that confidence that I know that I've obviously been there and done it around here to a certain extent and was in the hunt is obviously something to build upon this week."

Rose has been grouped with American Phil Mickelson, a five-times major champion who has yet to clinch his national championship, and Sweden's Henrik Stenson for Thursday's opening round.

(Editing by Larry Fine)