Washington (33-21) at Philadelphia (28-25)

The Philadelphia Phillies are baffled by the inconsistency of their offense.

Expected to have one of the National League’s most potent offenses, the Phillies have had several outbursts this season. More often than not, however, they are unable follow up those performances with similar efforts.

Philadelphia will look for a more consistent offensive showing when it hosts the Montreal Expos in a three-game weekend series at Veterans Stadium.

The Phillies have scored in double figures six times this season. However, in the six games that followed each outburst, they have totaled just 12 runs. On Wednesday, the Phillies routed the New York Mets 11-3, only to fall 5-0 in Thursday’s series finale.

“It’s frustrating,” Phillies first baseman Jim Thome said. “You come out and score a lot of runs. You want to keep it going.”

Philadelphia manager Larry Bowa said he cannot understand why his players are not hitting up to their capabilities.

“You’ve got guys who have proven records,” Bowa said. “You have to sit back and see what happens.”

The Expos, who won two of three against the Phillies last weekend at Olympic Stadium, head to Philadelphia after losing three of four to the Florida Marlins.

On Thursday, Montreal avoided being swept in a four-game series for the first time in more than two seasons with a 3-2 victory. With 12 hits, Expos snapped a streak of six games with seven or fewer.

STANDINGS: Expos - 2nd place, 3 1/2 GB, NL East. Phillies - 3rd place, 8 GB, NL East.

EXPOS PROBABLE STARTER: Javier Vazquez (5-2, 3.25 ERA). Vazquez pitched very well against the Phillies on Sunday, giving up two runs and five hits through seven innings of a 5-3 win. In 17 career games against Philadelphia, Vazquez is 8-3 with a 4.43 ERA.

PHILLIES PROBABLE STARTER: Brandon Duckworth (3-1, 5.47 ERA). Duckworth has won his last three decisions. On Saturday, however, he did not get a decision after having one of his better starts of the season. In a 3-2 loss to the Expos, he gave up two runs and six hits over six innings. In seven career games against Montreal, Duckworth is 1-3 with a 6.14 ERA.

OFFENSIVE LEADERS: Expos - Jose Vidro, .332 avg.; Vladimir Guerrero, 8 HRs and 33 RBIs; Orlando Cabrera, 34 runs; Endy Chavez, 9 SBs. Phillies - Mike Lieberthal, .316 avg.; Thome, 11 HRs and 38 RBIs; Jimmy Rollins and Bobby Abreu, 34 runs; Rollins, 7 SBs.

SEASON SERIES: Expos, 2-1.

STREAKS AND NOTES: Expos - 2B Vidro is 4-for-21 (.190) in his career against Duckworth. … The Expos have not homered in four straight games. … RHP Luis Ayala pitched a perfect eighth inning on Thursday to extend his streak of consecutive batters retired to 27, the longest streak in the majors this season. Phillies - 1B Thome has hit in eight straight games and has reached safely in 19 in a row. … C Lieberthal is batting .400 (10-for-25) in his career against Vazquez. … LF Pat Burrell, who is batting .207, returned to the lineup on Thursday after sitting out Wednesday night. He went 1-for-4 with a double.

ROAD/HOME RECORDS: Expos - 14-12 on the road; Phillies - 14-11 at home.

INJURIES: Expos - RHP Tony Armas Jr. (shoulder), 15-day DL; RHP Orlando Hernandez (shoulder), 15-day DL. Phillies - INF Tyler Houston (finger), 15-day DL; RHP David Coggin (shoulder), 15-day DL.