Rory McIlroy is threatening to lap the field but new Ryder Cup vice-captain Graeme McDowell wants to give him "a run for his money" in the $7 million BMW PGA Championship. 

As McDowell fired a 67 to get to six-under par, McIlroy put on a ball-striking clinic, cruising to an effortless-looking, bogey-free 65 to lead the field by three strokes and his former stablemate by six on 12-under.

He played so well that playing partner Alex Noren —a man who closed with a 62 to win last year— described McIlroy's seven-birdie show as "the best round I've ever seen."

Noren joked that he was going to "quit the game" so impressed was he by a round that made his bogey-free 68 for a share of fifth look pedestrian.

It's just as well for the rest that the Holywood star (29) didn't birdie either of the two closing par-fives for the second day running.

Had he birdied just one of them, he'd have matched Paul McGinley's 10-year-old 36-hole scoring record. 

"I played really well — bogey-free around here, I think I only missed one green, not by a lot," McIlroy said after he went out in 32 with birdies at the fourth, seventh and ninth, before making another four in a row from the 12th.

"It was one of the best rounds of golf I've played this year, ball-striking-wise." 

Frenchman Sebastian Gros (28) shot 66 and English rookie Sam Horsfield (21) a 68 to trail by trial McIlroy by three shots in second with European number one Tommy Fleetwood —a man who came from behind to deny McIlroy in Abu Dhabi in January— only four behind after a 66.

While McIlroy missed chances inside 10 feet on the first two greens, he made amends by rolling in a nine-footer at the ninth, a 25 footer at the 13th and a 40 footer at the 15th.

The rest of his birdies all came inside six feet with the pick of them from around 18 inches at the short 14th.

"I was thinking, here we go," he confessed with a grin after those two early misses on the greens. "But I played great after that and took my chances when I was hitting good shots."

Having come from behind to win in 2014, he admits that winning from the front would be "a huge confidence boost."

Nobody knows better than McIlroy's former stablemate McDowell that the chasing pack has its work cut out.

"When Rory is on his game, he's incredibly tough to catch," said McDowell, who made seven birdies in a 67 on a rain-softened West Course alongside Ryder Cup captain Thomas Bjorn and a frustrated Shane Lowry.

"But obviously hoping to give him a run for his money this weekend and hopefully we can get some drier weather and a little bit of wind and keep us all honest."

Tied ninth, McDowell says he still wants to make a fifth Ryder Cup appearance but admits that being part of the backroom team has its pluses.

"It's taken the weight off my shoulders a little bit," McDowell said. "I'm out there kind of free-wheeling, enjoying my golf and managing to play well."

No wonder he was tickled to detect the surprised tone in Bjorn's congratulatory 'Nice playing, G-Mac' as they shook hands at the end.

"Listen, I'd dearly love to be on the team playing in France, but in the meantime very committed to helping the captain with everything I can do for him," he said.

Lowry is eight shots behind in 30th on four-under after a mediocre 71 but insists he’s putting well enough to make up ground.

"I know around here that it doesn't take much to move up the leaderboard," Lowry said. "I have to stay patient and keep playing the way I am."

There’s no way back now for Paul Dunne, however, after he double-bogeyed the first and shot 75 to miss the cut by three shots on two-over par with Pádraig Harrington two shots further back after a 70.

Seamus Power was disqualified for signing for an incorrect score in the Forth Worth open where Justin Rose shot a six-under 64 to lead by a shot on 10-under par from Argentina's Emiliano Grillo, who shot 67

Power initially posted a 74 to finish on seven-over but was later discovered to have pencilled in a three instead of a four on his 17th hole when he was well on his way to missing the cut.

Headfort's Brendan McGovern missed the cut in the KitchenAid Senior PGA Championship in Michigan, finishing on 13-over after rounds of 78 and 77.

Scott McCarron shot 68 and Kevin Sutherland a 66 to lead on eight-under from Tim Petrovic (69), Chris Williams  (68), Joe Durant (67) and Jerry Kelly (65).

Scores

BMW PGA, Wentworth (West Course, Par 72)

Detailed scores

132 Rory McIlroy (Nir) 67 65, 

135 S Gros (Fra) 69 66, S Horsfield (Eng) 67 68, 

136 T Fleetwood (Eng) 70 66, 

137 R Rock (Eng) 69 68, A Noren (Swe) 69 68, K Aphibarnrat (Tha) 68 69, F Molinari (Ita) 70 67, 

138 A Levy (Fra) 70 68, M Korhonen (Fin) 68 70, L Jensen (Den) 68 70, F Zanotti (Par) 69 69, L Bjerregaard (Den) 65 73, D Fichardt (RSA) 66 72, N Bertasio (Ita) 68 70, Graeme McDowell (Nir) 71 67, M Fitzpatrick (Eng) 67 71, B Grace (RSA) 69 69, 

139 M Pavon (Fra) 72 67, L Westwood (Eng) 70 69, J Heath (Eng) 72 67, D Burmester (RSA) 66 73, H Li (Chn) 73 66, T Olesen (Den) 69 70, T Immelman (RSA) 71 68, A Sullivan (Eng) 71 68, E Van Rooyen (RSA) 70 69, R Fisher (Eng) 71 68, B Hebert (Fra) 70 69, 

140 S Gallacher (Sco) 71 69, C Wood (Eng) 72 68, R Ramsay (Sco) 69 71, Shane Lowry (Irl) 69 71, R Cabrera Bello (Esp) 72 68, B Neil (Sco) 71 69, M Kieffer (Ger) 69 71, E Pepperell (Eng) 72 68, A Saddier (Fra) 70 70, 

141 M Kinhult (Swe) 74 67, P Waring (Eng) 73 68, M Manassero (Ita) 75 66, I Poulter (Eng) 74 67, H Tanihara (Jpn) 69 72, J Suri (USA) 74 67, M Southgate (Eng) 69 72, T Jaidee (Tha) 69 72, A Björk (Swe) 71 70, M Wallace (Eng) 72 69, 

142 R Cho (Kor) 74 68, B An (Kor) 74 68, D Lipsky (USA) 70 72, R Bland (Eng) 67 75, M Lorenzo-Vera (Fra) 72 70, G Green (Mas) 72 70, P Casey (Eng) 72 70, 

143 B Stone (RSA) 73 70, A Wu (Chn) 72 71, J Kruyswijk (RSA) 73 70, S Fernandez (Esp) 74 69, R Fox (Nzl) 70 73, D Brooks (Eng) 70 73, J Wang (Kor) 74 69, J Dantorp (Swe) 74 69, T Detry (Bel) 72 71, A Pavan (Ita) 73 70, M Warren (Sco) 71 72, H Porteous (RSA) 74 69, A Dodt (Aus) 70 73, 

CUT

144 H Varner Iii (USA) 75 69, M Kaymer (Ger) 70 74, C Hanson (Eng) 74 70, D Frittelli (RSA) 71 73, J Winther (Den) 74 70, J Luiten (Ned) 73 71, R Jacquelin (Fra) 76 68, T Aiken (RSA) 72 72, O Fisher (Eng) 75 69, B Dredge (Wal) 68 76, O Farr (Wal) 73 71, J Lagergren (Swe) 72 72, R Sterne (RSA) 76 68, G Bourdy (Fra) 75 69, 

145 G Coetzee (RSA) 75 70, B Rumford (Aus) 75 70, N Elvira (Esp) 75 70, C Paisley (Eng) 68 77, S Kjeldsen (Den) 76 69, D Drysdale (Sco) 74 71, A Quiros (Esp) 71 74, J Choi (Kor) 73 72, M Ilonen (Fin) 71 74, C Ford (Eng) 69 76, R Evans (Eng) 76 69, G Fernandez - Castaño (Esp) 69 76, D Howell (Eng) 73 72, 

146 D Horsey (Eng) 73 73, T Hatton (Eng) 73 73, J Campillo (Esp) 72 74, A Romero (Arg) 73 73, D Willett (Eng) 75 71, S Lee (Kor) 71 75, P Larrazábal (Esp) 72 74, S Hend (Aus) 73 73, A Bland (Aus) 74 72, Paul Dunne (Irl) 71 75, M Siem (Ger) 76 70, M Fraser (Aus) 75 71, R Karlsson (Swe) 73 73, 

147 J Smith (Eng) 71 76, T Pieters (Bel) 75 72, E Els (RSA) 75 72, J Scrivener (Aus) 75 72, A Chesters (Eng) 73 74, A Otaegui (Esp) 75 72, C Shinkwin (Eng) 74 73, G Havret (Fra) 75 72, P Oriol (Esp) 75 72, N Colsaerts (Bel) 71 76, P O'Hara (Sco) 71 76, J Morrison (Eng) 69 78, 

148 Pádraig Harrington (Irl) 78 70, J Guerrier (Fra) 72 76, J Donaldson (Wal) 75 73, 

149 A Rai (Eng) 72 77, T Pulkkanen (Fin) 77 72, R Coles (Eng) 74 75, P Khongwatmai (Tha) 74 75, A Johnston (Eng) 73 76, E Molinari (Ita) 78 71, 

150 S Jamieson (Sco) 75 75, Z Lombard (RSA) 78 72, R Paratore (Ita) 74 76, S Chawrasia (Ind) 74 76, W Ormsby (Aus) 75 75, D Im (USA) 75 75, S Brazel (Aus) 73 77, J Norris (Aus) 75 75, 

151 R Wattel (Fra) 78 73, C Koepka (USA) 78 73, C Pigem (Esp) 73 78, 

152 R Wallis (Eng) 78 74, R Gouveia (Por) 75 77, 

154 P Hanson (Swe) 73 81, C Sordet (Fra) 77 77, 

155 T Bjørn (Den) 75 80, 

156 A Connelly (Can) 78 78, L Slattery (Eng) 77 79, 

157 S Brown (Eng) 80 77, 

163 G Hay (Sco) 85 78, 

** Y Miyazato (Jpn) RT.