Paul Casey, winner of the £1million first prize on his debut in the World Match Play Championship last year, was going well again at Wentworth today.

After a fog delay of nearly two hours Casey had a hat-trick of birdies from the fourth to take command of Jerry Kelly — and after the American had drawn back level by the 12th, he went away again to lead by three at the halfway stage of their 36-hole clash.

Padraig Harrington, Justin Rose and Colin Montgomerie were all in a spot of trouble early on, though.

Harrington trailed Dane Anders Hansen by two after 15 holes, Rose trailed Hunter Mahan by two after 18 and Montgomerie was four down to six-time winner Ernie Els after 15.

A pitch to five feet on the long fourth was the start of Casey's fine run, and he followed it by holing a 40-footer from just off the next green and then hit an eight-iron to eight feet at the sixth.

Kelly did have his hopes boosted, however, when Casey — conqueror of Retief Goosen, Mike Weir, Colin Montgomerie and Shaun Micheel a year ago — putted right off the green at the 396-yard seventh.

Birdies at the 11th and 12th squared things up. But Casey hit a powerful drive and eight-iron to six feet on the 470-yard next, then won the next two with pars.

Once more Kelly fought back, making birdie on the 383-yard 16th. But his top-seeded opponent, with nothing better than a 10th-place finish since March, replied in kind on the par-five 17th.

Neither was able to birdie the long last.

Harrington had bogeys at the first, third, fifth and ninth in an untidy outward 38 — the worst scoring of the morning — and after starting the back nine in brighter mood with a birdie, he dropped another shot at the 15th to go two down once more to Hansen, winner of the BMW PGA title on the course in May.

Swedes Henrik Stenson and Niclas Fasth — who missed the eve-of-tournament pro-am with bronchitis — were four and two up on American Woody Austin and Argentina's Andres Romero respectively after 14 holes.

South African Rory Sabbatini led Soren Hansen by one after 16, and US Open champion Angel Cabrera came back from two down to lead Retief Goosen by two as they went for a 30-minute break at halfway.