Josh Donaldson Blue Jays 2015
Hard-hitting third baseman Josh Donaldson and the Toronto Blue Jays look to expand their AL East lead over the New York Yankees this weekend. Getty Images

One and a half games separate the first-place Toronto Blue Jays from the New York Yankees atop the American League East before their four-game series, and the outcome could have a lasting effect on both sides’ hopes for the playoffs. With a 7-4 mark in their last 11 games to keep pace with Toronto, New York will host the series beginning Thursday night at Yankee Stadium.

Since both sides are coming off losses on Wednesday, the victor of the series, whether its Toronto or New York, could take a small lead in the division with a little over three weeks left in the regular season.

Whomever loses could get tossed into the highly competitive wild-card race. The Yankees are currently four games ahead of the Texas Rangers for the top wild-card spot, but their potential ascension in the division would drop Toronto back into the hunt with the Rangers, the Minnesota Twins, and the Los Angeles Angels, with even Cleveland, Tampa Bay, and Baltimore technically within striking distance.

Thus far, the Blue Jays have owned the season series with an 8-4 record, but the Yankees took two of three when they met in the middle of last month.

The critical series features the two best offenses in the majors, and though neither side has a dominate rotation or bullpen, the series will feature some intriguing pitching matchups.

In the opener, the Blue Jays will send out ace David Price, who’s gone 5-1 with a 2.08 ERA and 58 strikeouts over seven starts since he was acquired at the trade deadline, while the Yankees counter with 21-year-old Dominican righty Luis Severino.

When he was called up on Aug. 9, Severino picked up two losses in his first three starts but has since ripped off three straight wins and allowed just two runs over his last 18.1 innings. Severino’s quick acclimation to the big leagues could help New York spell the loss of 14-win starter Nathan Eovaldi, who is expected to sit out the next four weeks due to elbow inflammation.

On Friday, Marco Estrada (12-8), tops on the Blue Jays with a 3.18 ERA, will matchup against Ivan Nova (6-7), who has struggled to come back from elbow surgery with a 4.50 ERA in 13 starts this season.

New York manager Joe Girardi reaches maybe the heart of his rotation with Michael Pineda squaring off against the Blue Jays Marcus Stroman on Saturday, with the Yanks’ Masahiro Tanaka and Toronto’s R.A. Dickey starting the series finale.

Both Pineda and Tanaka spent time on the disabled list this season, but have still posted 10-8 and 11-6 records, respectively, and each are strikeout machines. Pineda leads the club with 132 and Tanaka’s only seven back.

Dickey’s served as one of Toronto’s most reliable starters, tying Mark Buehrle with 18 quality starts, and he’s picked up five wins in his last eight starts with no losses.

Stroman, 24, will make his first start of the season after tearing up the ACL in his left knee in March and the time couldn’t be more perfect for Toronto after Buehrle required a cortisone shot in his pitching shoulder following a loss to Boston on Monday, according to ESPN.

The Blue Jays are certainly relieved to regain a starter who went 11-6 with 111 strikeouts last season, and it makes New York’s job that much more difficult with first baseman Mark Teixeira’s return still mired in doubt.

Ranking first on the team with 31 home runs and second with 79 RBIs, Teixeira hasn’t played since Aug. 17 when he suffered a bone bruise in his right leg and the Yankees said on Tuesday they weren’t sure if he could return during the regular season.

"Yeah, I do wonder," general manager Brian Cashman told reporters. "Again, first and foremost, it's been a long time and he's still having issues. Again, I can't predict what's going to happen here. There is a lot of time left. ... I just don't know. I just can't predict."

With catcher Brian McCann, DH Alex Rodriguez, and third baseman Chase Headley still on board, the Yankees lineup has largely hummed without Teixeira, but his absence could still be felt against a Toronto lineup featuring dominate hitter and third baseman Josh Donaldson.

With Jose Bautista and Edwin Encarnacion combining for 63 home runs and protecting him in the lineup, Donaldson is hitting .429 with a home run and seven RBIs this month and currently leads the AL with 115 RBIs.