Lee Westwood made light of jet lag to book his return to The Open following a two-year absence after winning his qualifier in Scotland.
However, his former Ryder Cup and current LIV Golf team-mate Ian Poulter and his son Luke - and Portrush-born ex-US Open champion Graeme McDowell - all came up short in their bids to make the final major of the year.
Westwood, 52, who has played in golf's oldest championship 27 times previously, finished top at Dundonald Links after posting seven under for 36 holes. He had flown in from Dallas where he had been competing in Sunday's LIV Golf event.
"I've been up since half-past one this morning with jet lag so I was starting to feel it," said Westwood, whose move to the Saudi Arabia breakaway series removed his chances of qualifying for majors through regular tour events.
"I haven't tried to qualify for the last couple of years for one reason or another.
"Royal Portrush is a fantastic golf course and I played well there last time, finished fourth in 2019, so that was another reason to come and play.
"The Open Championship is the greatest tournament on the golfing calendar. I'm not getting any younger, I'm 52 now."
Poulter at least finished the day with some pride intact as, having trailed Luke all day in the scoring, finished level with his 21-year-old son on one under. Luke followed an opening 67 with a 76 at Royal Cinque Ports in Kent, with his dad shooting 72-71, as they and McDowell finished just short.
"I played good on the first 18, the last 18 not great," said Luke.
LIV golfer Dean Burmester topped the leaderboard at Royal Cinque Ports after a brilliant eight-under second-round 64 lifted him to 10 under.
That was three better than Nathan Kimsey - whose professional golfer girlfriend Lauren Taylor won the 2011 Women's Amateur at Portrush - and Curtis Knipes, who qualified for the 2019 Open.
Derbyshire amateur Sebastian Cave and Dane John Axelsen completed the five qualifiers.
At Dundonald, amateur Connor Graham won a play-off to join fellow Scot Daniel Young, Spain's Angel Hidalgo, Swede Jesper Sandborg and Westwood in qualifying.
Another LIV golfer, Lucas Herbert, finished top at West Lancashire, near Liverpool, with an eight-under total after rounds of 69 and 67.
That was one better than China's Sampson Zheng, with England's George Bloor third and amateur Richard Teder - who holed out from the fairway for eagle at the third extra hole to become the first Estonian to play at The Open - and Finland's Oliver Lindell coming through a four-man play-off.
England's Jacob McGoldrick endured a roller-coaster end to his qualifying as a hole-in-one at the 15th put him in line to progress, only to card two late bogeys to miss the play-off by one.
At Burnham & Berrow in Somerset, Cornwall-born PGA Tour winner Harry Hall qualified alongside winner Justin Walters, who finished nine under, Dane Jakob Skov Olesen, amateur Frazer Jones and fellow Englishman OJ Farrell.
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