There was no doubt who England's David Horsey thought of first after taking a share of the first-round lead in the BMW PGA Championship at Wentworth.

As Phil Mickelson began indefinite leave from golf because of his wife Amy's breast cancer, Horsey spoke of his mother's battle with the disease following a five-under-par 67.

"She's at home watching the live scoring and watching on the TV and hopefully it has kept her going," said the 24-year-old Cheshire golfer, who jointly heads the European Tour's flagship event with compatriot Anthony Wall and also Spaniard Gonzalo Fernandez-Castano.

"She never really talks about it that way but hopefully I've helped in that respect.

"She was diagnosed at the end of last year and and just had her last chemo(therapy) yesterday. She's got three weeks of radiotherapy coming up shortly and hopefully that will be it but she won't get the all-clear obviously until three or four years down the line.

"It's been tough - it's always at the back of my mind. My mum's always been very strong through it and my dad has obviously been there for her.

"I do try hard not to think about it when I'm playing and what she would want for me is to keep on playing."

Tour rookie Horsey, a team-mate of Rory McIlroy at the 2007 Walker Cup and winner of last season's Challenge circuit, was the first of the 150-strong field to tee off at 7am.

He was one over after five holes of his debut but birdied the next two, added another on the 12th and finished with three more.

Londoner Wall, only two groups behind him, also came home in a four-under 33, while British Masters champion Fernandez-Castano went birdie-eagle on the last two.

The biggest surprise of the day was the 78 of Henrik Stenson, who on his last appearance two weeks ago played arguably the best final round of the year to capture the Players Championship in Florida.

The Swede, however, was not as shocked as others might be - he has never finished higher than eighth in eight appearances at the event and he spent last week on holiday in the Bahamas.

Stenson, at fourth in the world the highest-ranked player in the field, gave a tennis analogy.

"Some like hard courts, some like clay. This is not my surface," he said.

"I find it difficult to pick the shots and to judge how the ball will react."

Ryder Cup team-mates Padraig Harrington, Ian Poulter and Sergio Garcia have stayed away again this year but, asked if he had considered joining them, Stenson stated: "BMW has been a great supporter of the Tour and me personally, so I think it's important to be here."

For a while he was the worst score in the clubhouse but 2005 US Open champion Michael Campbell took eight on the long 17th and came in with a 79, then 2007 French Open champion Graeme Storm finished six-seven for 80 and Ireland's Gary Murphy had a nine on the 383-yard 16th in his 82.

Lee Westwood looked as if he might be topping that when he had four successive bogeys from the 12th to crash to seven over.

After birdies at the last two for 77, he quipped: "At least I beat Henrik by one.

"I just didn't play very well - that can happen here."

He was joint second to Colin Montgomerie in 2000 but missed five of the next six cuts and has not had a top 10 since.

As for Montgomerie, he hit back from his closing 80 at the Irish Open with a three-under 69, the same as world number seven Paul Casey and last season's European number one Robert Karlsson.

"One 69 is okay but what I have to do is put another one on the board, then another one," said the Ryder Cup captain. "If I can do that, I'll be thrilled.

"I have to set my goals the way they were - to win. I feel capable of it still and it's just a matter of going out and proving it to myself.

"I haven't been doing that."

Before Ireland he missed two cuts in a row and bowed out of the Spanish Open with an 81.

Masters champion Angel Cabrera failed to make his presence felt in the way he wanted, shooting 74, and American John Daly was only one better than that along with Ernie Els.

With rounds taking more than five and a half hours, there was the chance of one of the late starters stealing the show after nearly all the fans had gone home.

Southport's Lee Slattery had the chance when he reached three under with birdies at the 11th and 12th.

Slattery's hopes of grabbing at least a share of the lead went when he double-bogeyed the 15th.

Collated first round scores in the European Tour BMW PGA Championship, Wentworth GC, Surrey, England

(Gbr & Irl unless stated, par 72):

67 Anthony Wall, David Horsey, Gonzalo Fdez-Castano (Spa)

68 Ross Fisher, Charl Schwartzel (Rsa), Miguel Angel Jimenez (Spa), Niclas Fasth (Swe), Barry Lane

69 Soren Kjeldsen (Den), Colin Montgomerie, Maarten Lafeber (Ned), Scott Drummond, Ben Curtis (USA), Alvaro Quiros (Spa), Robert Karlsson (Swe), Paul Casey, Anthony Kang (USA), Alexander Noren (Swe)

70 Peter Lawrie, Raphael Jacquelin (Fra), Gary Lockerbie, Ricardo Gonzalez (Arg), Lee Slattery, Jamie Donaldson, Markus Brier (Aut), Fabrizio Zanotti (Par), Alastair Forsyth, Jean-Francois Lucquin (Fra), Thomas Levet (Fra)

71 Robert Jan Derksen (Ned), Retief Goosen (Rsa), Marcel Siem (Ger), Thongchai Jaidee (Tha), Peter Hanson (Swe), Brett Rumford (Aus), Robert Rock, Stephen Dodd, Andres Romero (Arg), Alejandro Canizares (Spa), Gregory Bourdy (Fra), Sam Little, Marcus Fraser (Aus)

72 Anton Haig (Rsa), Thomas Aiken (Rsa), Anders Hansen (Den), Benn Barham, Scott Strange (Aus), Pelle Edberg (Swe), Martin Kaymer (Ger), Shiv Shankar Prasad Chowrasia (Ind), Rory McIlroy, Marc Warren, Paul Lawrie, Richard Green (Aus), Phillip Archer, Mark Foster, Pablo Martin (Spa)

73 Mikael Lundberg (Swe), James Kingston (Rsa), Soren Hansen (Den), Robert Dinwiddie, John Bickerton, Pablo Larrazabal (Spa), John Daly (USA), Thomas Bjorn (Den), Ernie Els (Rsa), Miles Tunnicliff, Jean-Baptiste Gonnet (Fra), Hennie Otto (Rsa), Michael Lorenzo-Vera (Fra), Shiv Kapur (Ind), Francois Delamontagne (Fra), Nick Dougherty, Phillip Price, Seve Benson, Paul Broadhurst, Ignacio Garrido (Spa), Paul McGinley, Jyoti Randhawa (Ind), Richard Sterne (Rsa)

74 Zane Scotland, Mikko Ilonen (Fin), Angel Cabrera (Arg), David Frost (Rsa), Darren Clarke, Simon Dyson, Andrew McLardy (Rsa), Johan Edfors (Swe), Simon Khan, Felipe Aguilar (Chi), Jose-Maria Olazabal (Spa), Alessandro Tadini (Ita), Michael Jonzon (Swe), Tano Goya (Arg), Luke Donald, Peter O'Malley (Aus)

75 Steve Webster, Magnus A Carlsson (Swe), Graeme McDowell, Paul Waring, Jason McCreadie, Gareth Maybin, James Ablett, Rafael Echenique (Arg), Kenneth Ferrie, Simon Wakefield

76 Jeev Milkha Singh (Ind), Richie Ramsay, Gary Orr, David Howell, Oliver Wilson, Per-Ulrik Johansson (Swe), Brett A Taylor, Mads Vibe-Hastrup (Den), Daniel Vancsik (Arg), George Ryall, Prayad Marksaeng (Tha), Taco Remkes (Ned), Rafael Cabrera Bello (Spa), Christopher Doak, Gregory Havret (Fra), Ross McGowan

77 Christian Cevaer (Fra), Francesco Molinari (Ita), Martin Erlandsson (Swe), Louis Oosthuizen (Rsa), Oliver Fisher, Andrew Oldcorn, Stephen Gallacher, Richard Finch, David Dixon, Guy Woodman, Nick Ludwell, Lee Westwood

78 Chapchai Nirat (Tha), Mark Brown (Nzl), Paul Simpson, Jose Manuel Lara (Spa), Henrik Stenson (Swe)

79 Alvaro Velasco (Spa), Michael Campbell (Nzl), Jarmo Sandelin (Swe), Peter Hedblom (Swe), David Lynn, Bradley Dredge, Simon Lilly

80 Graeme Storm

82 Gary Murphy

86 John Kelly (USA)

RTD: Miachel Hoey