Graeme McDowell beat Rory McIlroy 3 and 2 to reach the quarter-finals of the Volvo World Match Play Championship in Spain.
Clearly agitated after missing two opportunities while four down, McIlroy got two back with birdies, but McDowell finished him off after holing from the fringe at the 16th - again from further away than his opponent.
It was a clash, of course, between not just Northern Ireland's two leading players - McDowell is ranked fifth in the Official World Golf Ranking, McIlroy sixth - but also Ryder Cup partners and close friends.
Reigning US Open Champion McDowell had spoken of how he had become accustomed to getting "beaten up" whenever they practiced together, but this was their first tournament head-to-head and it proved to be a very different story.
It was not the only all-Ryder Cup meeting in the last 16, and in the other World Number One Lee Westwood trailed Ian Poulter by two with five to play.
If Westwood lost, Luke Donald and Martin Kaymer had a chance to take over top spot, but while Kaymer beat Dane Søren Kjeldsen 3 and 2, Donald trailed Swede Johan Edfors by two with three to go before taking the next two to level.
McIlroy's problems began immediately when he three-putted to fall behind and it was also clear there that he had no intention of being generous.
After being asked to hole from around three feet there, McDowell was made to putt from an even shorter distance at the next for a half.
McIlroy hit his second into the lake on the long third to go two down and the gap went to three when he three-putted the par five eighth.
He did manage an 18 footer from just off the ninth green, but it was only for a half with McDowell holing from five feet, and even though he was the closer of the two at the 11th McIlroy was the one to miss.
As he departed, so did defending champion Ross Fisher, but only after a staggering finish against Masters Tournament champion Charl Schwartzel.
Two down with two to play - he had came from four down to beat American Ryan Moore - Fisher birdied the 17th and eagled the last after hitting a fairway wood to ten feet.
But South African Schwartzel had followed that shot with an even better one and holed from five feet for a matching eagle and one up victory.
Donald kept his World Number One hopes alive, getting up and down from a bunker at the first extra hole after being two down with three to play.
McIlroy said: "I missed five chances in the middle that really cost me. It was a great battle, but I couldn't get a putt to go in.
"I was getting very frustrated - when you are going against someone of that calibre you need to take your chances."
On not conceding a number of short putts he added: "You can't give anyone anything" and on the lack of the usual chat between them he said: "I wasn't going to really engage in any conversation - that was the plan from the start - and it looked like he had the same idea."
Italy's Francesco Molinari beat Australian Aaron Baddeley 3 and 2 and Belgian Nicolas Colsaerts defeated Venezuela's Jhonattan Vegas on the last, which left only Westwood and Poulter - and they were all square when Westwood birdied the 14th and Poulter bogeyed the next.
