Rory McIlroy warns "heroic" effort needed to catch Wyndham Clark at BMW Championship

Rory McIlroy admitted it's going to take an "heroic" effort to catch Wyndham Clark at the BMW Championship despite surging up the leaderboard on moving day. 

McIlroy began the second leg of the PGA Tour's playoffs at Bellerive Country Club in St. Louis with a fine 6-under 64 but stalled somewhat yesterday as Clark seized control. 

But he fought back on Saturday with a 5-under 65 to reach 12-under, five behind the American. He shares second place alongside his former Ryder Cup rival Patrick Cantlay. 

Clark also posted the same score as McIlroy to reach 17-under and looks almost certain to capture his third win of the season following his exploits at the CJ Cup Byron Nelson and the U.S. Open at Shinnecock Hills. 

"I think I needed to be patient the last three days, because my game has, it's been good in parts, but then it's been a struggle in other ways," said the Masters champion. 

McIlroy hit the turn in 1-under and it took him until the 10th to find his first fairway of the day. 

He put circles on his card on 11, 13, 15, 16 and 17. The only blemish of the day came at the 14th whereby the Northern Irishman three-putted from 45-feet.  

"I didn't hit my first fairway today until the 10th hole," McIlroy, 37, added. "Playing this golf course from the rough isn't fun. 

"But I hung in there, my short game saved me a couple of times. 

"And I got some momentum coming in with those birdies on 15, 16 and 17 and then a good up-and-down at the last. 

"I'm in a good spot going into tomorrow in terms of where I'm at on the leaderboard, but it's going to take a heroic effort from one of us to catch Wyndham."

McIlroy took a three-week break from the sport after The Open at Royal Birkdale and was abysmal, by his standards, on his rust. 

He showed considerable rust as he laboured to a 66th-placed finish in a field that only contained 68 players.

Still, he has turned around his fortunes quickly.

"Honestly, I did the same thing a couple years ago going from Memphis to this tournament," he said. 

"This tournament was at Castle Pines. Similar sort of thing. 

"Finished nearly dead last at Memphis, and then got it together and played a bit better at Castle Pines. 

"So yeah, I would say if Memphis is always my first week coming back, I would say the next week's always, I bet that it's going to be better."

Elsewhere, world number one Scottie Scheffler carded a 68 and currently shares 15th place alongside Cameron Young and Justin Thomas. 

The four-time major champion cut a frustrated figure and let his temper boil over a tad at the par-4 12th. 

Scheffler hit a poor greenside chip that raced by the cup and proceeded to smash his wedge into the turf three times. 

The BMW Championship is the second leg of the PGA Tour's playoffs. 

Only the top 30 in the standings at the conclusion of this tournament are assured of a spot in the $40m Tour Championship at East Lake.