However, they still lost to an Arsenal side who secured their own place in the top three as Leeds came off second best in a tempestuous encounter packed with controversy.

In a fixture full of bad blood, with 34 yellow cards and two reds in the past five encounters, flashpoints abounded, with Martin Keown accused of elbowing Mark Viduka in the face and standing on Lee Bowyer’s arm.

The Australian also exacted his own retribution and Bowyer was guilty of play-acting in the first-half, while six yellow cards were shown.

All enough to ensure that the Valencia scout ensures his side’s preparations for dirty challenges are stepped up considerably ahead of the second leg.

The game itself was deservedly won by the Gunners, with Fredrik Ljungberg putting them ahead early on and Sylvain Wiltord striking the second on 57 minutes.

Leeds struck back through Ian Harte’s free-kick within two minutes and had their best spell late on, but they were largely given the runaround by Arsenal and must now rest their weary limbs ahead of Tuesday’s game.

Indeed, O’Leary must hope that both of his Champions League dreams did not fizzle out in the same match. That his gamble on not resting players did not spectacularly backfire.

For with Arsenal home and dry, Liverpool, even more crucially, beating Newcastle and Ipswich still in contention, Leeds now face an uphill task to finish in the top three.

What is more, with only David Batty, Alan Smith and Danny Mills to come back into the side, adrenalin, guts and their never-say-die attitude may now have to carry them through.

Writing Leeds off is a perilous business, but Arsenal, who lost to Valencia in the quarter-finals, are well placed to tell the visitors just how hard it is to beat the Spanish side.

And Leeds will certainly need to be far more incisive, as well as controlled, if they are write another chapter in their amazing European adventure.

At Highbury, it was all blood and guts, with Patrick Vieira - banned for kicking Olivier Dacourt in the head at Elland Road, while O’Leary clashed with Robert Pires - fouled twice in the first minute by Eirik Bakke.

The tone was set yet another combustible encounter, with four players booked in the first-half - and no prizes for guessing that Dacourt and Vieira were the first two.

Arsenal were meanwhile in command as Leeds chased shadows in midfield in trying to cope with the influence of the peerless Vieira while David Batty was absent through suspension.

Nigel Martyn tipped a powerful drive by Thierry Henry behind for a corner and Ljungberg squandered a free header just a couple of yards out.

However, Ljungberg quickly redeemed himself as Arsenal made their pressure tell on 17 minutes as he played a neat one-two with Henry before side-stepping past Martyn and clipping his shot home.

The focus soon returned to the ferocious tackling, with Bowyer inflaming matters by clutching his head after tangling with Henry even though the midfielder was apparently guilty of play-acting.

With Keown and Tony Adams virtually untroubled in the Arsenal defence, Bowyer wasted a half-chance and Keane was hauled off even before half-time and replaced by Jason Wilcox.

There was little that Leeds could do to stem the tide, however, and it was only a superb reaction save by Martyn just before the break that denied Lee Dixon’s acrobatic scissors-kick.

Arsenal pressed home their advantage as Wiltord linked superbly in exchanging passes with Vieira before turning and striking a first-time shot into the far corner.

That, so it appeared, was it. However, Leeds’ answer was immediate as Ian Harte curled a sublime free-kick into the top corner within two minutes of the restart.

Arsenal still threatened on the break, but Leeds were given fresh hope as long as they could keep their tempers.

That was in doubt after Viduka claimed to have been elbowed in the face by Keown and, after arguing with his own team-mates and even the club’s physio, he exacted revenge himself a minute later and was booked.

With Bowyer also claiming that Keown had stood on his arm, tempers were again at boiling point.

Against this backdrop, the visitors almost equalised when Harte’s 40-yard free-kick flew across the face of goal, just evaded Kewell and hit the post before rebounding to safety.

But that was as close as Leeds came to snatching a point. They travel to Valencia with all best wishes, but on this occasion, it was O’Leary who needed to be the good loser.