A pair of surprise division leaders square off this evening, as the National League West front-running Los Angeles Dodgers welcome the East's top team, the Washington Nationals, to Dodger Stadium for the start of a three-game series.

Los Angeles enters tonight's contest at 13-6, while the Nationals slipped to 14-5 on Thursday when they were denied a sweep and fell for the first time in five tries in the finale of their three-game series with San Diego, falling 2-1 at Petco Park.

Washington reliever Tyler Clippard (1-2) struck out Nick Hundley to escape a bases-loaded jam in the seventh, but the right-hander couldn't protect a one- lead in the next frame, as Mark Kotsay delivered two-run double.

"I like my chances with Clippard out there," Nats manager Davey Johnson said.

Tonight, the Nationals will turn to unbeaten right-hander Ross Detwiler, who is 2-0 with a magnificent 0.56 earned run average. Detwiler was terrific in beating the Miami Marlins last Friday, scattering three hits over six scoreless innings.

Detwiler, who has pitched to a 3.24 ERA in two appearances against the Dodgers, may have his hands full, as he will be opposing the NL's reigning Cy Young Award winner in Clayton Kershaw, who is 1-0 with a 1.61 ERA.

Kershaw looked like an award winner his last time out, as he beat the Houston Astros by giving up just three hits in seven scoreless innings. He also struck out nine batters in the win.

"I don't think Kersh is where he wants to be yet," Dodgers manager Don Mattingly said. "He's been pretty good, but he hasn't quite been what you would consider midseason form. ... We're not sitting here complaining, but I don't think he's been quite right yet and where he wants to be."

Kershaw is just 2-2 in six games (five starts) against the Nats with a 4.61 ERA.

The Dodgers enter tonight's tilt on the heels of losing two of three to the Atlanta Braves, including a 4-2 loss in Wednesday's finale.

Matt Kemp, though, continued his torrid pace with his 10th home run and 23rd RBI of the season, both of which lead the majors. Dee Gordon drove in the other run for the Dodgers, who have dropped three of four.

Ted Lilly had a strong start, but did not factor in the decision despite giving up just one run on three hits over seven innings. Javy Guerra (1-3) was tagged with the loss.

Guerra actually took a line drive off the face in that one, but stayed in the game and should be ready to go tonight.

Los Angles won four of its six meetings with Washington last season. The Nationals are also 5-15 at Dodger Stadium since relocating from Montreal in 2005. That season also was the last time the franchise won a series at Chavez Ravine.