Immelman leads the charge

Immelman, who on his last visit to Augusta National a year ago was put out of action for over a month by a stomach parasite, shot his second successive 68 for an eight-under-par halfway total of 136.

American Brandt Snedeker was only a shot behind, though, and right in the thick of things on five under were left-handers Steve Flesch and Phil Mickelson, as well as England's Ian Poulter.

A day after holing-in-one at the 16th Poulter had a birdie two on the same hole and added a 69 to his opening 70.

Fellow Englishman Paul Casey called Immelman's aggregate "unbelievable", but he was only four back after a closing 10-foot birdie for a 69.

Lee Westwood improved to four under as well, but then came a double bogey seven on the 13th after he twice went into the creek.

By missing a four-foot birdie opportunity on the last he had to settle for a 73 and a two-under total. That was still good enough for a share of ninth spot.

As for Justin Rose, joint first round leader with Immelman, he had the misfortune - just like last year when he also led overnight - to be out in the last group and had to contend with a freshening breeze.

Rose bogeyed the fifth and a failure to get up and down from sand on the ninth brought an outward 38 that left him six behind alongside Westwood.

Mickelson is, of course, seeking his third win in five years and as well as being delighted by a 68 he just had to be pleased that Tiger Woods was still in the pack at one over with eight to go.