Charl Schwartzel staged a dramatic fightback Saturday at the Thailand Golf Championship in a bid to overhaul runaway leader Lee Westwood, cutting his lead from 11 to just four shots in the third round. While Westwood struggled to maintain his imperious early form which had put him on 20-under overnight, Masters champion Schwartzel showed grit and determination to force his way into contention with a six-under 66. Westwood had to battle hard for a one-over 73 at the Amata Spring Country Club course, and it could have been even worse for the English star. In a rare slip, Schwartzel bogeyed the 18th hole to give the world number three some much-needed breathing space, and the South African also missed some birdie opportunities. "It was one of those days," said Westwood after seeing his big lead severely trimmed. "I hit a lot of good shots but couldn't sink the putts. I got between yardages quite a few times." The Englishman, who could replace Rory McIlroy as world number two if he wins this event, accepted he was not going to be able to maintain his incredible form of the first two days. "After a 60 and 64 you have to be a bit realistic. I am still taking a four-shot lead into the final round, a situation I would have been happy with at the start of the tournament." Schwartzel for his part was very happy with his progress. "I’m pleased with today. I didn’t expect to finish just four shots back when I started the round," he said. Despite making big inroads into Westwood’s lead, the South African said he knew he still had a lot to do to catch the Englishman. "I have to shoot a low score in the final round, but you have to expect Lee to shoot something like 68 or 69. But at least now there’s a light at the end of the tunnel. Four shots is not that much." Schwartzel had shown his intentions right from the start when he birdied four of the first five holes. In all he sunk seven birdies and suffered just the one bogey. For the first time in the tournament, Westwood, who suffered his first bogey of the event at the second hole, was put under some pressure and it appeared to affect his game. Little known American Michael Thompson held third place after a steady 69, but is seven shots behind the leader. Dutch player Guido Van Der Valk was in fourth place after firing an impressive 66, one shot ahead of England’s Simon Dyson who shot a 68. A stroke further back was India’s Jyoti Randhawa, while American John Daly slipped to joint 11th with a slightly disappointing 72. Spain’s Sergio Garcia displayed improved form following a 70, but he is still well down the field, as is Open winner Darren Clarke who hit a 73. Japanese star Ryo Ishikawa had another poor day, shooting 77 for the second successive round.