TORONTO (Interstat) — Carlos Narváez hit a decisive two-run double in the sixth inning, Nathaniel Lowe drove in two runs and the Boston Red Sox used a collective pitching effort to stifle the AL-leading Toronto Blue Jays 4-1 on Tuesday night at Rogers Centre.

The victory improved the Red Sox to 86-71 on the season, while the slumping Blue Jays, who managed just three hits, lost for the fifth time in six games to fall to 90-67. Toronto saw its lead in the AL East shrink to just one game after the New York Yankees rallied to beat the Chicago White Sox 3-2 earlier in the day.

Boston’s pitching staff was the story, holding Toronto’s lineup in check from start to finish. Starter Lucas Giolito set the tone, working 4 2/3 innings and allowing one run on three hits while striking out three. The only damage against him came in the fourth inning when Nathan Lukes doubled and later scored on a force out from Andrés Giménez.

The Red Sox bullpen took over from there, combining for 4 1/3 innings of perfect, hitless relief. Justin Wilson (4-1) recorded four outs to earn the win, Garrett Whitlock struck out two in a perfect inning of work, Justin Slaten handled the eighth, and Aroldis Chapman pitched a 1-2-3 ninth for his 32nd save of the season.

Offensively, Boston broke through first against Toronto ace Kevin Gausman (10-11). In the second inning, Masataka Yoshida led off with a double and later scored on an RBI single from Nathaniel Lowe.

The game remained tight until the sixth, when the Red Sox broke it open. Romy Gonzalez doubled and advanced to third on a single by Ceddanne Rafaela. Lowe then delivered his second run-scoring single of the night to plate Gonzalez. After a chaotic fielder’s choice that resulted in Rafaela being thrown out at home on a challenged play, Narváez stepped up and laced a two-run double to center field, scoring both Lowe and Wilyer Abreu to give Boston a 4-1 cushion.

Gausman was charged with the loss, lasting 5 2/3 innings and surrendering all four runs on nine hits while striking out seven. The Blue Jays’ bullpen of Mason Fluharty, Louis Varland, and Tommy Nance kept Boston off the board for the final 3 1/3 innings, but the Toronto offense could not mount a comeback.

The Red Sox, who improved to 40-39 on the road, collected nine hits in total, with Yoshida and Lowe each recording two. The Blue Jays’ offensive struggles were highlighted by their three hits, all of which came in the fourth inning.

The game, played in front of a crowd of 42,927, took 2 hours and 52 minutes to complete. The result defied pregame projections, as Interstat’s game simulator had predicted a 6-4 Toronto victory, and their ELO system gave the Blue Jays a 54.2 percent probability to win.

The two teams continue their critical three-game series on Wednesday night at Rogers Centre. The series represents Boston’s final road trip of the regular season, while Toronto will host the Tampa Bay Rays over the weekend to conclude its schedule.