After firing 4-under 68's at Scotland's storied Royal Troon on Thursday, they lead England's Nick Job and Americans Andy Bean, John Cook and Kirk Hanefield by one shot.

But perhaps the man they should all be looking out for is the defending champion Tom Watson.

His opening 70 has tied him with another of the pre-tournament favourites, Berhard Langer, for 7th, but perhaps more than anything it has showed clearly that the multi-major winner is one of the men to be watched this weekend.

Watson certainly produced more than enough evidence to suggest that he could win his second successive and third British Seniors title overall on the very same course where he won his 1982 Open Championship

While Vaughan's see-saw ride to a 68 included eight birdies as well as a double and triple bogey and Romero made it too the top with five birdie and a bogey, rock solid Watson posted just one birdie after putting for 18, but managed to keep his card totally free of bogies

The 58-year-old Watson said: "I didn't hit every fairway, but I hit every green today. How about that! I've never done that before. I hit 18 greens and putted for 18 birdies which I don't think I have ever done at any time in my life."

Vaughan, in the meantime, started his up and down day with birdies on the 2nd and 4th holes, but slipped back to level par with a double bogey seven on the fifth.

He recovered quite dramatically with three birdies in five holes but then blew the lead with an awful triple bogey seven on the 12th and needed three more birdies at 13, 16 and 18 to grab the early clubhouse lead from Watson.

"It was either feast or famine today," he said with a smile afterwards.

"Outside of those two sevens, it was a good round. It's just the first day though. We've got a few more days left."

Three more days may not be enough for Greg Norman, though.

The charismatic Australian failed to keep the brilliant momentum going that put him in the lead after three rounds of last week's 137th Open.

In sunny conditions at Troon, Norman bogeyed six of the first 10 holes and was 6 over before he finally picked up a shot at the par-4 13th.

He made one more birdie at the last with a pitch to 3 feet.

"Things just weren't going my way early on," Norman said.

"I just had to hang in there and gut it out the best I could. The ball just wasn't rolling my way, but there's more than one round in a golf tournament."

Romero, who lost a playoff to Loren Roberts in this championship two years ago at Turnberry, won the Dick's Sporting Goods Open at Endicott, New York, three weeks ago for his second seniors triumph and is another clear threat.

Romero made just one bogey in a 3-under 68, driving into a fairway bunker at the par-5 sixth hole and having to lay up.

"I feel strong, I feel good and I feel happy," said the Argentine, whose highlight was a 15-foot birdie putt at the 17th.

ALL THE FIRST ROUND SCORES
(USA unless stated, par 71):

68 Bruce Vaughan, Eduardo Romero (Arg)

69 Nick Job (Eng), Andy Bean, Kirk Hanefeld, John Cook

70 Bernhard Langer (Ger), Joey Sindelar, Gene Jones, Tom Watson, John Morse, Mark McNulty (Irl)

71 Tony Johnstone (Zim), Eamonn Darcy (Irl), John Bland (Rsa)

72 Mike Williams (Zim), Luis Carbonetti (Arg), Andrew Murray (Eng), J A Fraser (Sco), Ross Drummond (Sco), John Ross

73 David Ogrin, Jeff Hall (Eng), Tim Conley, Mike Reid, Sam Torrance (Sco), Costantino Rocca (Ita), Adrian Morrow (Irl), Jon Chaffee

74 Juan Quiros (Spa), Craig Stadler, Vicente Fernandez (Arg), Wayne Grady (Aus), Ronnie Black, Peter Mitchell (Eng), Philip Blackmar, Denis Durnian, Mark O'Meara, Mark Wiebe, Nobumitsu Yuhara (Jpn), Pete Oakley, Jim Rhodes (Eng), Tomohiro Maruyama (Jpn), David Merriman (Aus)

75 Mike Hulbert, Mike Goodes, Ken Green, Sandy Lyle (Sco), Isao Aoki (Jpn), Martin Poxon (Eng), Mark James (Eng), John Hoskison (Eng), Greg Norman (Aus), Seiji Ebihara (Jpn), Andrew Reynolds (Eng), Gordon J Brand (Eng), Denis O'Sullivan (Irl), Ian Woosnam (Wal), Scott Simpson, Kiyoshi Murota (Jpn), John Mctear (Sco), Tim Simpson, Yutaka null Hagawa (Eng)

76 Gary Hallberg, Ian Brotherston (Sco), Tom Kite, Jim Lapsley (Nzl), Noel Ratcliffe (Aus), Bill Longmuir (Sco), Tom McKnight, Bill null Mccoll (Sco), Bertus Smit (Rsa), Adam Adams, Clarence Rose, Angel Franco (Par), Gary Koch

77 Phil Hinton (Eng), Martin Gray (Eng), James Chancey, Jose Rivero (Spa), Carl Mason (Eng), Bob Gilder

78 Brady Exber, John Mcdonald (Sco), Jerry Bruner, Ray Carrasco, Bob Boyd, Katsuyoshi Tomori (Jpn), Donnie Hammond, David Good, Manuel Pinero (Spa), Antonio Garrido (Spa), Terry Gale (Aus), Jeff Sluman, Tony Allen (Eng), David j Russell (Eng), Simon Owen (Aus), Des Smyth (Irl)

79 Buddy Harston, Guillermo Encina (Chi), Tim Giles (Eng), David a Russell (Eng), Scott Hoch, John Chillas, Andrew Hall (Eng), Bill Lockie (Sco), Jimmy Blair, Torsten Giedeon (Ger), John Harris, Motomasa Aoki (Jpn)

80 Giuseppe Cali (Ita), Tommy Horton (Eng), T.c. Chen (Tpe), Bobby Lincoln (Rsa), Horacio Carbonetti (Arg), Gordon Townhill (Eng), Arthur Pierse (Irl), Ron Streck, Steve Martin (Sco), Bob Cameron (Eng), Peter Teravainen, Peter Dahlberg (Swe), Maurice Bembridge (Eng)

81 Gary Player (Rsa), Tony Price (Wal), Bruce Heuchan, Harumitsu Hamano (Jpn), Bob Charles (Nzl), Shigenori Mori (Jpn)

82 Joel Hirsch, Domingo Hospital (Spa), Jimmy Heggarty (NIrl)

83 Garry Harvey (Sco), David Downie (Sco), Steve Stull, Robin Clark (Eng), Ossie Moore (Aus)

84 Steve Prendergast (Irl), Mike Gallagher (Eng), J.p. Morgan (Eng)

85 Robert Fox (Eng), Niall Lavin (Irl)

87 Paul j Mckellar (Sco), Stewart Graham (Eng)