By Ed Osmond

LYTHAM ST ANNES, England (Reuters) - Americans Bubba Watson and Mark Calcavecchia were the only early starters to make significant inroads on the leaderboard in the British Open third round on Saturday.

U.S. Masters champion Watson picked up five shots in his opening 13 holes to get to five under par, five behind leader Brandt Snedeker.

The 52-year-old Calcavecchia, the 1989 Open champion, made two early birdies to move to three under.

With the weather set fair and only light winds expected, American Snedeker was due to tee off at 1520 local time (1020 EDT) alongside Australian Adam Scott who trails him by one shot.

The pair will follow 14-times major champion Tiger Woods, on six under, and 22-year-old Dane Thorbjorn Olesen who fired a second-round 66 to finish at five under.

World number two Rory McIlroy continued to struggle on the Lytham links with a scrappy 73 to finish five over and third-ranked Lee Westwood's wait for a major title looks certain to continue after he went round in 71 to end on four over.

"I couldn't really muster up anything out there today," McIlroy told reporters. "It wasn't difficult to get myself up for it but it is hard to keep yourself going when you know you are out of the tournament.

"There are definitely chances out there for a low score but it is tough. The scores aren't great out there today but you need to control your ball and keep it on the fairway."

Two former Open champions endured miserable rounds after just making the cut, five-times winner Tom Watson carding a 76 and John Daly 77 to finish at nine and 10-over-par respectively.

India's Anirban Lahiri caused the biggest cheer of the day with a hole-in-one, the first of the tournament, at the 165-yard par-three ninth taking him to one under overall.

(Editing by Tony Jimenez)