Thailand’s Kiradech Aphibarnrat added a 68 to his opening 64 at Wentworth to post a halfway total of 12 under par and lead by one from England’s Laurie Canter, with Adam Scott on 10 under and Justin Rose another stroke back.
But it was the constantly fluctuating battle to make the team for Whistling Straits which continued to dominate the agenda at a final qualifying event in which Harrington’s accountancy qualifications were set to prove very useful.
That would mean McIlroy qualified via the world points list instead of Lowry, who in turn could knock Westwood out with a top-eight finish or better, depending on Westwood’s result.
Whoever missed out would join the likes of Ian Poulter – who missed the halfway cut – Sergio Garcia and Rose in vying for one of Harrington’s three wild cards on Sunday evening, although Rose can still qualify automatically with a win.
Wiesberger had been three over par after six holes of his first round, but finished birdie, eagle and added a superb 67 on Friday to end the day inside the top 20 on six under, two shots behind Lowry.
Westwood was in danger of missing the cut when he covered the front nine in 37 to fall back to level par, but made four birdies on the back nine to record a second-successive 70.
“I’m here to try and win the BMW PGA Championship and Sunday night, if you’re in the team, then you start thinking about the Ryder Cup,” Westwood said.
“There’s so many variables as well with the way we’ve set up the qualification this time around. This tournament is heavily loaded compared to everything else we’ve done and I think it’s something to maybe look at in the future.
“You can see how players are reacting to it out on the golf course. You know there’s people right in there and they are shooting scores where clearly they have got other things on their mind.
“I’ve played with Shane, he’s managed to block everything out well and play well and Shane Lowry is the kind of player that you want on your Ryder Cup team. I’m pleased to see him play well.”
Lowry echoed Westwood’s sentiments after a 66 which left him four shots off the lead, adding: “There’s almost too many points available, especially for someone like me who is in the team.
“It is what it is. We’ve known it for a couple of years. I’m just out there to do a job. I’m out there to try to win the tournament and play as best I can and, come Sunday evening, hope I’m on the team automatically.
“If I’m not, I hope I get a pick. I feel pretty laid back about it. I’m not anxious about the whole thing.
“I feel like I’ve played really well over the last while and consistently well and I feel like I’ve put my hand up. It’s up to Paddy what he wants to do on Sunday evening.”
Away from the Ryder Cup battle, Canter carded eight birdies and two bogeys in a second round of 66, despite getting up at 4am to watch Emma Raducanu’s US Open semi-final in New York.
“I had a 4.30 alarm anyway so thought ‘why not set it a bit earlier’,” said Canter, who was a promising tennis player himself before opting to concentrate on golf.
“I watched her match from the end of the first set. Never in doubt was it? She’s been awesome, looks like she’s got it all. She looks like she has the world at her feet and hopefully we will be watching her for years to come.”
As for his own game, Canter was pleasantly surprised to be in contention following three straight missed cuts, especially at a tournament he used to attend by “sneaking through car park two” on to the course.
“Given my recent form, it’s just nice to be playing at the weekend,” the 31-year-old from Bath added.
“I’ve come here and watched this event over the years so it’s great to even be part of it, but to be up at the top of the leaderboard at the moment is great.”