BOSTON (AP) Anthony Rizzo scored the tiebreaking run in the ninth, then endured some uncertain moments in the bottom of the inning before he could celebrate.
He and his Cubs teammates lingered on the field until a replay review confirmed the on-field decision: Rizzo had caught Luis Valbuena's throw from third base to first on a grounder in time to get Dustin Pedroia for the final out.
''It was nerve-wracking,'' Rizzo said after Chicago's 2-1 win over the Boston Red Sox on Tuesday night, ''especially with Big Papi coming up.''
Had the call been overturned, David Ortiz would have batted with runners at first and second and two outs.
''I didn't even see the replay,'' said Pedroia, who gestured in frustration after crossing the bag. ''I feel like I was right there. It was bang-bang. I don't know.''
Rizzo started the ninth with a single, went to third on a double by Starlin Castro and scored on Valbuena's sacrifice fly off Koji Uehara (3-2). Mookie Betts made the catch in medium right field, but his throw was off line and Rizzo scored easily.
''Oh, gosh, what a great at-bat,'' Cubs manager Rick Renteria said. ''He fell behind (and) was just still able to put enough of the barrel on the baseball to get it deep enough to score the run.''
The double was the 37th extra-base hit for Castro, who entered the game tied with Troy Tulowitzki of the Colorado Rockies for the major league lead among shortstops with 36.
Pedro Strop (1-3) pitched a perfect eighth and Hector Rondon worked the ninth for his 11th save in 13 chances.
Boston continued to struggle offensively one night after getting no hits against Jake Arrieta for 7 2-3 innings until Stephen Drew singled. The Red Sox ended that game with season lows of two hits and three base runners in a 2-0 loss. In their last five games, they've scored more than two runs just once.
''It gets a little frustrating at times, particularly with the number of opportunities we continue to create,'' manager John Farrell said. ''And that's the thing that we have to continue to focus on internally, is that the opportunities are there and yet at times we're not cashing in.''
But their dominant home pitching persisted.
For the 14th straight game at Fenway Park, the Red Sox allowed no more than three runs, extending their franchise record. The last longer streak in the American League was 15 games by the Chicago White Sox, the last game in 1966 and the first 14 in 1967.
The Red Sox took a 1-0 lead in the fifth against Edwin Jackson. Jackie Bradley Jr. doubled and scored from third on a single by Pedroia.
The Cubs tied it in the sixth after going hitless against Clay Buchholz since Chris Coghlan led off the game with a single.
''Both Jax and Buchholz were grinding it out against each other,'' Renteria said.
Justin Ruggiano started the sixth with a double, moved to third on a single by Darwin Barney and scored when Coghlan grounded into a force play at second base. Ryan Sweeney's single put runners at first and third, but the threat ended when Rizzo lined out to first baseman Mike Napoli, who stepped on first to double up Sweeney.
Chicago threatened again in the seventh when a single by Castro, a passed ball and a hit batter put runners at first and third with one out. Andrew Miller replaced Buchholz and struck out pinch-hitter Junior Lake and Ruggiano to end the inning.
NOTES: Boston used an all-rookie outfield of LF Brock Holt, CF Bradley and RF Betts. Holt played only the infield in limited time in the majors the past two seasons. Betts was mostly a minor league second baseman but has played only the outfield in his three games since being called up from Triple-A Pawtucket. ... Jackson pitched six innings, just the second time he's lasted that long in his last eight starts. ... The Red Sox sent LHP Rich Hill from Triple-A Pawtucket to the Los Angeles Angels for cash and released LHP Chris Capuano, who was designated for assignment last Wednesday. ... Boston 3B Xander Bogaerts is hitless in his last 19 at-bats after going 0 for 4. ... Travis Wood (7-6) faces Boston's Brandon Workman (1-1) on Wednesday night in the finale of the three-game interleague series.