SAN DIEGO -- The back end of a bullpen can be a fluid place, with roles changing based on performance and not always well-defined.

It is interesting to note, however, the increasing importance of Chin-hui Tsao in the way Dodgers manager Grady Little is slotting his relievers in winnable games.

Tsao, who had missed much of the past three years with Colorado because of arm problems, made a strong run at a roster spot during Spring Training, but was a victim of numbers and was sent to Triple-A Las Vegas. He's been called up twice since, and this time perhaps to stay.

In Saturday night's game with the Padres, ahead 3-2, Little had Rudy Seanez warming up in the sixth inning while starter Brett Tomko dueled with Greg Maddux, but for the seventh inning, Seanez sat down and Tsao started throwing, eventually called on to relieve Tomko and escaping an inherited mess with a wild rundown double-play.

Tsao then pitched a 1-2-3 eighth inning and hasn't allowed a run to score in any of his six appearances, while yielding only one hit in 6 2/3 innings. Even more impressive, he's inherited nine baserunners and none has scored, which is why Little has the confidence to bring him into jams, the role that fell to Giovanni Carrera in recent years and one that might be the toughest for any reliever.

"He's given us no reason not to use him in more important roles," said pitching coach Rick Honeycutt. "To me, each time out there's more validity that he can handle any situation. We strive that the most important batter is the first one and he's been getting that first batter out, he's attacking him."

Catcher Russell Martin said he can understand why Tsao was destined to be the Colorado Rockies' closer until injuries sidetracked his career.

"He's making nasty pitches," said Martin. "He's throwing strikes and going after guys and not shying away. When he needs a ground ball, he keeps his pitches down. When he needs a strikeout, he can reach back. He's got a good slider, a splitter or change-up, plus he can throw really hard."

Rundown: Tsao and Martin combined on an unusual rundown play that quashed the threat inherited from Tomko in the seventh inning. With runners on first and third and one out, Rob Bowen sent a well-placed bunt between the mound and third-base line that nearly squirted past Tsao, but he made an athletic play to stop the ball and caught Mike Cameron halfway between third and home.

After running Cameron toward third, Tsao threw to third baseman Wilson Valdez, who ran Cameron toward the plate and threw to Martin, who ran down Cameron heading back to third. Meanwhile, Kevin Kouzmanoff had just about made it from first to third base, but he abandoned third and retreated toward second, which by now was occupied by Bowen. Martin, appearing to be running the bases backward, chased down Kouzmanoff for the double-play.

"It was fun for me," Martin said. "You don't see that happen very often."

Little on Pierre: Little said he thinks he knows why Juan Pierre hit .180 over his first two weeks with the Dodgers and is hitting .377 since.

"When he first got here, he put too much heat on himself to try to be better than he's capable. He tried to do too much," said Little. "We simply want the guy we brought in to play center field, not to be better than he was. He's starting to show himself."

Pierre seemed to be slapping the ball during his slow start, but he's now driving the ball to the gaps.

"When a guy tries too hard, he muscles up instead of letting his hands do the work," said Little. "Whether it's a hitter or pitcher, you get negative results when you try to do too much."

Betemit back: After missing Saturday night's game with food poisoning, Wilson Betemit rejoined the club and was available to play, but didn't start against left-hander David Wells.

"Bad chicken wings from hotel room service," said Betemit. "I was throwing up all day yesterday. I couldn't eat until 10 at night."

Ramon Martinez started at third base and Little also had Brady Clark start in right field instead of Andre Ethier. Ethier had never faced Wells, while Clark was 2-for-5 against him previously. Little said he planned to play Betemit on Monday night against Arizona and Brandon Webb.

Kuo starts: Pitcher Hong-Chih Kuo began his injury rehabilitation assignment in Las Vegas on Sunday by pitching two innings, allowing one run on one hit (a double) with one walk and three strikeouts. He made 30 pitches. Yhency Brazoban made his second rehab appearance in three games, striking out a pair in a 1-2-3 inning for Las Vegas on Sunday.

Arrive early Monday night: The Dodgers will hand out fleece blankets to the first 50,000 fans in attendance Monday night and are encouraging carpools and early arrivals. Parking gates open at 5:10 p.m. PT and stadium gates open at 5:40 p.m. Visit the Dodgers' Web site for more details.

Coming up: Randy Wolf (3-2, 4.20) opposes Cy Young winner Webb (1-1, 3.60) and the Diamondbacks when the Dodgers return home Monday night for the start of a three-game series.