CAMBRIDGE, Mass. — The Dartmouth baseball team clinched its fifth straight Rolfe Division title by defeating Harvard in the first game of a doubleheader on Saturday afternoon at O’Donnell Field, 11-3. In the nightcap, the Big Green finished the sweep with a 12-3 triumph as Dartmouth (21-15, 13-5 Ivy) extended its winning streak to 12 games. Harvard dropped to 11-29 overall on the season and 7-11 in the Ivy League.

In addition to the division title, the Big Green also kept their hopes alive for hosting the Ivy Championship Series that will take place on May 5-6. If Dartmouth wins the final two games of the series against the Crimson on Sunday in Hanover, and Princeton earns at least a split of its doubleheader against Cornell, the Green will own the best record in the conference and earn the right to host the best-of-three series.

Dartmouth struck first in the opener, scoring four times in the second inning. After sophomore Dustin Selzer led off with a single through the left side of the infield, the Big Green did not get another ball out of the infield. Sophomore Jeff Keller beat out an infield hit, but Harvard hurler Brent Suter retired the next two batters, leaving runners on the corners with two down. But senior David Turnbull got the first run home with an infield hit, then seniors Jake Carlson and Joe Sclafani were hit by pitches to force in the second run. A balk brought home another run, and freshman Thomas Roulis drove in the fourth with the third infield single of the frame.

The score remained 4-0 through five innings as sophomore southpaw Mitch Horacek held the Crimson batters scoreless on five hits. In the sixth, Dartmouth broke it wide open with seven runs — its largest scoring inning of the year — on just two hits. Two walks and an error loaded the bases, sending Baron Davis to the mound to relieve Suter. Roulis greeted Davis with a sharp two-run single to right, and junior Chris O'Dowd got an RBI by hustling down the line to beat the relay on a possible inning-ending double play. Another error and a hit batter loaded the bases before junior Ennis Coble drew a walk to force home a run. Zack Olson then came in from the bullpen, only to serve up a three-run double to freshman Nick Lombardi, giving the Green an 11-0 lead.

Harvard got three of those runs back in the bottom half on a Kyle Larrow two-run single and an RBI single off the bat of Jon Smart, both with two outs.

Horacek (4-2) pitched 6.2 innings of the seven-inning contest, allowing three runs on 12 hits and a walk while striking out five. Senior Max Langford came on to record the final out of the division-clinching victory.

The Crimson out-hit  Dartmouth, 12-8, but two Harvard errors led to six unearned runs. Roulis and Lombardi each drove in three runs to lead the Big Green offense, while five Crimson hitters had at least two hits led by Jack Colton with three.

Suter (2-6) took the loss, surrendering seven runs, five earned, over 5.1 innings on six hits and a pair of walks with five punchouts.

In the second game, Dartmouth wasted no time in jumping out to a big lead. Sclafani started the game by drawing a walk, Roulis singled him to third and O’Dowd sent him home with another single. After a strikeout, Keller was hit by a pitch to load the bases and Coble hit into a fielder’s choice to score Roulis. A wild pitch allowed O’Dowd to scurry home, then freshman Matt Robinson lined an RBI single up the middle. Lombardi lofted a pop fly down the right-field line, which was dropped for an error, and Robinson hustled all the way around from first to make it 5-0.

Dartmouth tacked on solitary runs in the second and third innings thanks to RBI singles by Keller and Carlson. In the fourth, Lombardi launched a grand slam to straight-away center for his second four-bagger of the season and an 11-0 lead.

Meanwhile on the mound, Dartmouth freshman left-hander Adam Frank was dominating the Harvard hitters. Through the first six innings, the only base runner came on a bunt single by Mike Martin in the fourth inning, who was quickly erased on a line-drive double play. The Crimson finally got to Frank in the seventh with four hits, including a three-run blast off the bat of Jeff Reynolds. But Frank righted his ship and got the final two outs, then finished the eighth for the longest outing by a Big Green pitcher this year.

Selzer finished the scoring with an run-scoring double in the ninth, and sophomore Louis Concato retired the side in order in the ninth to complete the road sweep.

O’Dowd and Robinson had three hits apiece as the Big Green collected 14 as a team, while Lombardi drove in four runs with his grand slam.

Frank improved to 4-1 on the season, allowing three runs on five hits and two walks over his eight innings with four strikeouts.

Connor Hulse (0-2) was stuck with the loss, getting knocked out in the second inning after giving up six runs, five earned, on five hits and a pair of walks while recording just five outs.

The two teams will finish their four-game series with a doubleheader at Red Rolfe Field at Biondi Park on Sunday at 1 p.m. on Dartmouth’s Senior Day.