03/12/2005 1:00AM

Sir Shackleton thwarts Lion Tamer

Javier Castellano completes a five-win day by riding Sir Shackleton to a 1 1/2-length score over Lion Tamer in the Richter Scale.

HALLANDALE BEACH, Fla. - Jockey Javier Castellano and trainer Nick Zito completed a big day at Gulfstream Park on Saturday when Sir Shackleton registered a 1 1/2-length victory over defending champion Lion Tamer in the Grade 2, $200,000 .

The win was the fifth on the day for Castellano and second from as many starters on the card for Zito. The pair combined earlier to win the sixth race with 3-year-old prospect Bellamy Road.

Sir Shackleton ($5.40), the co-favorite at 8-5 with Lion Tamer, set a seven-furlong track record of 1:21.64, eclipsing the 1:22.06 Madcap Escapade ran three weeks earlier.

Castellano urged Sir Shackleton along a bit more than usual during the early going to stalk front-runners Sir Oscar and Clock Stopper, who rushed up along the rail to surprisingly contest the early pace. Sir Shackleton swung three wide entering the stretch, came out a bit farther exiting the turn, then accelerated suddenly once he straightened for the drive to run down Clock Stopper and win going clear.

Lion Tamer broke a step slow, trailed in the run down the backstretch, advanced steadily while widest into the stretch, then rallied belatedly to outfinish Clock Stopper by a neck for second.

Sir Shackleton, a son of Miswaki, is owned by his breeder, Tracy Farmer.

"Javier was in a zone today," said Zito. "I knew there wasn't much speed in the race so I told him he better stay close and persevere all the way because we were dropping back to seven furlongs. I think his best distance is probably a mile and the Met Mile might be the long term goal."

Castellano's five wins moved him into second place in the jockey standings for the meet behind Edgar Prado.

"I knew I was on a lot of live horses and I was fortunate they all ran so well today," said Castellano.