After holing a birdie putt early in his afternoon foursomes, McIlroy turned angrily to one spectator who had questioned his technique and shouted: “"Who can't putt? Who can't putt? I can putt. I can putt. F****** come on!"
Earlier in the week, McIlroy admitted he had paid the price for failing to control his emotions in his singles match with Patrick Reed at Hazeltine two years ago.
Bjorn said he was not aware of the incident. “He hasn’t mentioned it to me and I wasn’t there,” said the Dane. “If it was important he would have mentioned it to me.”
And Bjorn showed faith in McIlroy - who together with Sergio Garcia crushed Tony Finau and Brooks Koepka in the morning fourballs - by giving him the responsibility of going out first in Sunday’s singles matches against Justin Thomas.
Europe’s players by and large responded to the partisan backing of the crowds at Le Golf National.
It was predicted in the build-up to this Ryder Cup that the crowds might be a bit more raucous than is typically the case in Europe.
Justin Rose noted that with the match taking place on French soil, rather than a traditional golfing heartland such as Scotland where the fans are “very knowledgeable, very respectful”, there might be more of a mainstream sports crowd.
“It will be interesting to see the dynamic in terms of how that feels for us,” Rose said. “I would welcome an atmosphere that’s more of a ‘sports’ crowd and a bit more raucous and a bit more as we face it in America.”
Rose certainly got his wish on Saturday. There was a definite edge to proceedings in Paris, almost from the first hole.
Tiger Woods declined to concede a short putt to Tommy Fleetwood early in their morning fourballs, prompting the Merseysider to turn to his caddie and ask: “What was that about?” after rolling home his putt.
Sky Sports were frequently forced to apologise for bad language. Woods was one of at least three players heard to use the word “f***” during the day - along with McIlroy and Justin Thomas - while golfing traditionalists would almost certainly have been offended by some of the other behaviour on display.
There was frequent loud cheering at missed American putts, while Dustin Johnson was twice seen spitting during his round.
Others, though, will be happy that Europe’s crowds are beginning to match their American counterparts for creating a hostile atmosphere, even if it did get personal on occasion.
Patrick Reed, the United States’ hero at Hazeltine two years ago and a man who likes to refer to himself as ‘Captain America’, had a miserable morning paired with Woods, the pair going down 4&3 to Fleetwood and Francesco Molinari. Reed’s misery would have been made more acute after one fan was heard to shout “Show us your t******, Reed!” at the American, who is one of the larger players on the US team.
The abuse was not targeted solely at American players. McIlroy was twice heckled by greenside fans. On the 12th, as he prepared to putt for birdie, one shouted: “But Rory, you live in Florida!” McIlroy drained the putt to put Europe four up in that match, pumped his fist and then turned and shrugged at his heckler.
Thomas, meanwhile, led the American resistance.
After holing one putt in his 2&1 fourballs victory with Jordan Spieth over Ian Poulter and Jon Rahm, the former world No 1 put his finger up to his mouth as if to tell the crowds to be quiet. He then went wild when he holed the putt on 17 that gave the US their solitary point in the morning session. “ Let’s f****** go!” Thomas screamed.