(Sports Network) - The Washington Nationals try for their first-ever series win at Petco Park this afternoon when they wrap up their three-game series with the San Diego Padres.

Washington evened the series at a game apiece on Wednesday, as Jesus Flores belted his first career grand slam in the Nationals' 6-4 win. Lastings Milledge hit a solo homer and scored two runs in the win, while Cristian Guzman finished 3-for-5 at the plate.

Odalis Perez (2-4) gave up three runs on six hits in 6 1/3 innings for Washington, which snapped a two-game skid.

Shawn Estes (1-1) gave up four runs on four hits in five innings for San Diego, which saw its two-game winning streak come to an end. Scott Hairston clubbed a two-run homer for the Padres, while Tadahito Iguchi went 3-for-5 and knocked in a run.

The Nationals haven't won a series in San Diego since a three-game set from August 17-19 when the franchise was known as the Montreal Expos. In fact Washington hasn't won two straight in San Diego since September 11-12, 1999.

John Lannan gets the call for Washington today. Lannan suffered his second loss in his last three starts on Saturday against Milwaukee, as he surrendered three runs and five hits in five innings, dropping him to 4-5 on the season, while raising his earned run average to 3.57.

Lannan has never faced the Padres.

San Diego will counter with Wilfredo Ledezma, who has lost his last two starts. Ledezma fell to 0-2 on the year on Saturday against Cincinnati, allowing five runs and five hits in just three innings, ballooning his ERA to 4.65.

Ledezma will be making his first-ever start against the Nats, but has faced them twice out of the bullpen without giving up a run in three innings of those outings.

San Diego won four of its six matchups with the Nats last season and is 21-6 in the series since the start of the 2004 campaign. The Padres have also been a stingy host, winning 11 of their last 15 at home against Washington.