(Sports Network) - Jon Lester makes the final regular-season start of what's been a terrific 2008 campaign for the young pitcher when the Boston Red Sox conclude a four-game series with the Cleveland Indians tonight at Fenway Park.

Lester has won 15 games so far during his breakthough year and ranks among the American League leaders with a 3.26 earned run average as well. The left- hander has been especially dominant on the Fenway Park mound, where he's amassed an excellent 10-1 record and a 2.54 ERA in 16 starts this season.

The 24-year-old did have a three-start win streak snapped with a shaky performance in Toronto last Saturday, however. Lester was reached for five runs and eight hits over seven innings against the Blue Jays and received the loss in Boston's 6-3 setback.

Prior to that defeat, Lester had yielded only three runs over 27 1 /3 innings during a four-start stretch in which he went 3-0.

He is 1-0 with a 4.96 ERA through three career starts against Cleveland, but struggled in his only matchup with the Indians this year. That came at Progressive Field on April 14, with Lester surrendering four runs and issuing five walks in just 4 1/3 innings of work.

The emerging ace's following start may come in Anaheim, since that appears to be where the Red Sox will be headed to begin their quest for a second straight World Series title. Boston has secured a spot in this year's postseason but is a longshot to win the AL East, as the club trails first-place Tampa Bay by three games with four left to play.

If the Sox wind up as the wild-card winner, they will face the AL West champion Angels in the opening round of the playoffs.

Boston kept its slim hopes to claim the division alive with last night's 5-4 decision over the Indians, in which Mark Kotsay delivered a tie-breaking RBI double in the bottom of the eighth inning to plate the winning run.

Kotsay added an RBI single earlier in the game to help the Red Sox defeat the Tribe for a second straight night. Cleveland did win the opener of this series by a 4-3 count on Monday.

David Aardsma (4-2) picked up the win for Boston after hurling 1 2/3 scoreless inning of relief, while Manny Delcarmen protected the lead in the ninth to notch his second save of the season.

Shin-Soo Choo, Jhonny Peralta and Victor Martinez each collected a pair of hits and an RBI for the Indians, who have dropped two in a row following a seven-game win streak. Starting pitcher Fausto Carmona was removed after just one inning and was shelled for four runs on five hits.

Cleveland expects to receive a longer outing tonight out of Jeremy Sowers, who comes in off a strong showing in his most recent start. The former first-round pick held Detroit to one run and five hits over six innings to record his second straight winning decision.

Sowers has posted two of his four season victories during the month of September, as he downed Baltimore with eight innings of one-run ball two starts back. The southpaw is just 4-8 with a lackluster 5.48 ERA in 21 starts for the year, however.

The 25-year-old has yet to face the Red Sox this season, but is 0-1 with a 5.06 ERA over two previous starts against Boston.

The Red Sox, who defeated the Indians in seven games during last October's AL Championship Series, have taken four of the five encounters between these teams so far this season.