Should Rory McIlroy summon the weekend spirit of Ontario, there would be little point in the remainder of this US Open field turning up for rounds three and four. Alas, professional golf remains an unpredictable beast. An outlandish Friday finish from Gary Woodland also supplied a degree of separation which, even with 36 holes to go, may prove pivotal. Woodland holed out from 49ft at the last for a 65 and two-shot lead, at nine under par.

McIlroy was already in contention for what would be a first major success since 2014 before stepping to Pebble Beach’s 1st tee on Friday. What transpired thereafter – if at varying levels – endorsed the Northern Irishman’s claims. Just days after swaggering to Canadian Open glory with closing rounds of 64 and 61, the 30-year-old is in the mix again. “Another couple of rounds in the 60s and I’ll take my chances,” said a bullish McIlroy.

Woodland’s statistics give the impression a penny has dropped. His first 27 major appearances came and went without a top 10 finish. He has delivered two in his last three. Woodland’s Friday inward half of 31 meant he initially tied, then waved goodbye to Justin Rose. Context was supplied by history; Woodland’s 133 strokes is one better than Tiger Woods at the same stage here in the US Open of 2000. Woods led the field by six.

McIlroy’s round wasn’t without drama. His opening 12 holes were as comfortable, particularly on the greens, as is possible in a US Open setting. He had reached six under par for the tournament and was within one of the lead when failing to rescue par from a greenside bunker at the 13th. One hole later, a double bogey seven took McIlroy back to the three under par position he had started day two at. McIlroy had just 107 yards into the pin with his third shot at the 14th. What happened next was somewhat ghoulish.

To McIlroy’s credit, and in displaying fortitude he typically isn’t afforded credit for, he responded with back-to-back birdies. A 69 leaves him four from the leaderboard’s summit at the halfway stage. A standard McIlroy strength, par five scoring, has thus far been a relative weakness; he played has those holes in plus two. “Yes, I need to improve that but I’ve obviously played some good golf to be two over there yet five under for the tournament,” McIlroy said.

“I bounced back well today. Those birdies on 15 and 16 felt huge to get me back in this tournament for the weekend. I need to keep it going; fairways, greens. It sounds boring and cliched but that’s what you need to do round here. The course is only going to get tougher.”

Rory McIlroy plays his second shot on the ninth hole. Photograph: Christian Petersen/Getty Images

Rose’s 70 meant he held the Friday lead on his own at seven under par before Woodland’s late afternoon surge. This has been a very un-Rose-like performance. The Englishman’s short game, frequently an achilles heel, has saved him time and again. Through two rounds, the 2013 US Open champion has required just 49 putts. Cynics may suggest that touch is unlikely to continue as the event hurtles towards conclusion.

“I have no expectations for the weekend really,” Rose insisted. “I like my position, I like the golf course, I like the way I’m trending. I still don’t feel like I’m clicking but if I can find that gear hopefully I can hoist some silverware. So there is work to be done this weekend for sure.

“You always need your short game in a US Open. You miss a fairway and it’s like losing half a shot. The goal for the rest of the hole is; how do you get that shot back. It’s normally with a great short game or a great putt. So the fact my short game feels sharp takes a bit or pressure off the long game.”

Louis Oosthuizen’s brilliantly erratic back nine included just one par. The end result was a 70 and six under total. Aaron Wise sits alongside McIlroy at minus five. Rickie Fowler surprisingly followed up a 66 with a 77.

Brooks Koepka became the first defending champion since 1988 to open with successive sub-70 rounds. Koepka, seeking a third win in a row at this major, has signed for 69s two days in a row meaning he lies five from the lead. “I feel great,” Koepka insisted. “I’m excited. I’ve got a chance. That’s all you can ask for. I just need to make a few putts.”

Woods cut an agitated post-round figure having bogeyed his last two holes on the way to a 72. At even par on aggregate, Woods has considerable weekend ground to make up. This isn’t an insurmountable task for the 15-times major champion but the depth of talent ahead of him on the leaderboard will be of concern. Woods blamed continually leaving himself downhill putts for Friday’s struggles. The result is an uphill task.

Comedic scene of the day, in its dying stages, was delivered by Patrick Reed. The 2018 Masters champion snapped his lob wedge over his knee in a fit of pique, following a botched chip at the 18th. Tut, tut.