Last year at Turnberry, Tom Watson made a turn-back-the-clock run at the British Open. In 2008 at Royal Birkdale, it was Greg Norman. During their runs, both said that the British Open was the one major in which they could still be competitive.

So far, midway through the second round of the 2010 Open Championship, three aging candidates – all seniors and former British Open champions, but none with the star power of Watson or Norman – have emerged.

Americans Mark Calcavecchia (7-under through 36 holes), Tom Lehman (5-under through 36 holes), and Mark O’Meara (3-under through 18 holes) are making noise.

Playing alternately in the sun, wind, and rain with Peter Senior and Anders Hansen in the first threesome of the day on Friday, Calcavecchia got around in four hours flat, shooting a 5-under 67, which tied 27-year-old leader Louis Oosthuizen and 21-year-old Rickie Fowler for the best score of the morning.

Calcavecchia, a playoff winner over Norman and Wayne Grady in the 1989 British Open at Royal Troon, hit 17 of 18 greens on Friday and stands in third place.

There was little to foreshadow his performance today. He has missed the cut in seven of 14 tournaments and finished no better than 24th on the PGA Tour this year. Since turning 50 on June 12, Calcavecchia has earned nearly as much ($90,900) in two Champions Tour events as he has in 14 PGA tournaments ($103,391).

Like Calcavecchia, Lehman, 51, had a bogey-free round Friday morning, shooting 68 as he averaged a whopping 330 yards off the tee and hit 13 of 16 fairways.

Lehman, the 1996 Open champion at Royal Lytham, has embraced the Champions Tour, winning two of 15 events, and earning more than $1.4 million on the senior circuit since turning 50. He’s also had two top-20 finishes in five PGA events this year.

The 53-year-old O’Meara, who won the 1998 Open in a playoff over Brian Watts at Royal Birkdale, has a late tee time Friday and is still waiting out a weather delay (wind) that has suspended play.

O’Meara has made $3.3 million in four years as a full-timer on the Champions Tour but didn’t get his first win until his 58th event, three months ago.