02/09/2006 1:00AM

Stevie undergoes surgery

One Union, shown training at Santa Anita, was found to have a bone chip and may require surgery. He is off the Triple Crown trail.

ARCADIA, Calif. - Stevie Wonderboy underwent surgery on Wednesday to have two stabilizing screws placed at the bottom of his right front cannon bone, a procedure that will prevent him from starting in the Kentucky Derby but will not keep him from a return to racing later this year, trainer Doug O'Neill said.

The champion 2-year-old male of 2005, Stevie Wonderboy was considered a top candidate for the Derby. After a workout on Monday, Stevie Wonderboy was found to have with a non-displaced condylar fracture of his lower right cannon bone, just above the ankle, O'Neill said.

O'Neill said the surgery was conducted by Dr. Ted Simpson at Hollywood Park.

"You never know until you're in there what the cartilage looks like, but he said it was healthly," O'Neill said of Simpson's post-surgical report. "The prognosis was very good. The injury was very subtle."

O'Neill said that Stevie Wonderboy was in his stall at Hollywood Park on Thursday and will remain there until next week when he is moved to owner Merv Griffin's farm. Stevie Wonderboy will be off for 90 days before he begins tack-walking, O'Neill said.

Stevie Wonderboy has won 3 of 6 starts and $1,058,940. He has won two stakes - the Grade 2 Del Mar Futurity and the Grade 1 Breeders' Cup Juvenile at Belmont Park last October, a victory that clinched his 2-year-old title.

In his lone start this year, Stevie Wonderboy finished second to Brother Derek in the San Rafael Stakes on Jan. 14.

One Union suffers knee chip

The list of important 3-year-olds in California sidelined by injury grew on Thursday when trainer Richard Mandella said that One Union has suffered a bone chip in a knee and is off the Triple Crown trail.

Owned by Herman Sarkowsky, One Union was a stylish winner of an allowance race at a mile on Feb. 3, his second start of the year. One Union led throughout that race to win by 2 1/4 lengths over Point Determined.

When asked of the severity of the injury, Mandella said, "It's just typical" of a bone chip. Surgery to remove the bone chip had not been scheduled as of Wednesday.

Kilroe next for Senor Swinger

Senor Swinger won his first stakes in Southern California in Wednesday's $81,450 Thunder Road, and the seventh of his career.

Ridden by Victor Espinoza, Senor Swinger ran a mile on turf in 1:34.10, rallying from sixth and holding off Terroplane. Toasted finished third in the field of 10.

Owned by Bob and Beverly Lewis and trained by Bob Baffert, Senor Swinger has won 10 of 29 starts and $940,742. Although Senor Swinger has placed in graded stakes at 1 1/2 miles on turf, Baffert wants to keep Senor Swinger at shorter distances.

"A mile is his deal," Baffert said.

Baffert said Senor Swinger will be pointed for the $300,000 Frank Kilroe Mile on turf on March 4.

* Santa Anita will offer a $1 million guaranteed pick-six pool on March 4, the day of the Santa Anita Handicap.