Rory McIlroy in heated argument at the Ryder Cup after claims ...

Rory McIlroy has lost his first match at this Ryder Cup — and then he lost his cool.

Key points:Rory McIlroy had to be ushered away to a car after exploding into a furious argument at the Ryder CupMcIlroy had claimed that Patrick Cantlay's caddie had been waving a hat in his eyeline during a crucial puttEurope leads the US heading into the final day of play needing four more points to claim victory

In scenes sure to stoke tensions ahead of the final-day singles, McIlroy accused Patrick Cantlay's caddie, Joe LaCava, of waving his hat in his line of vision ahead of the European star's crucial putt on the 18th green in the final four-ball match on Sunday morning.

That incident prompted another angry exchange involving McIlroy as he left the Marco Simone club.

McIlroy was seen to be visibly furious outside the clubhouse as Jim "Bones" Mackay, the caddie for Justin Thomas, attempted to intervene.

McIlroy was ushered into a waiting car by European teammate Shane Lowry, but only after plenty of shouting and finger-pointing. It wasn't immediately clear who McIlroy was aiming his anger toward.

The images were soon all over social media and will no doubt be part of the pre-match team talks before the singles. Europe lead 101/2-51/2 and need four more points to reclaim the trophy.

"Just fuel for the fire tomorrow," McIlroy said.

LaCava — like others in the US team — had removed his hat in a playful gesture after Cantlay holed a 45-foot birdie putt in near-darkness on the 18th hole.

Throughout the afternoon, thousands of European fans had waved their caps at Cantlay, in response to a report on Sky Sports claiming that he had refused to wear his cap out of protest because he wanted to be paid.

European captain Luke Donald said McIlroy "politely asked Joe to move aside" because the Northern Irishman still had a putt for birdie to tie the match, which he wound up missing.

"He (LaCava) stood there and didn't move for a while and continued to wave the hat, so I think Rory was upset about that," Donald said.

Donald said Europe's players were competitors and they wanted to win "in the right way."

"From what Rory told me, he did ask Joe to move," Donald added. "He took a long time to move. It was a little off-putting because he still had to putt."

Cantlay birdied the final three holes to earn a 1-up win with Wyndham Clark against McIlroy and Matt Fitzpatrick.

AAP