When Andrew Heaney underwent Tommy John surgery last July, it was unclear if he would return in 2017. Before the season started, Angels manager Mike Scioscia made it clear he didn't expect him back.
But on Friday, Heaney will make his first Major League appearance in over 16 months, one of several great games streaming live on MLB.TV.
Friday's jam-packed slate features several games with postseason implications and premier pitching matchups. The Red Sox and Yankees begin the fifth installment of their annual rivalry, while Corey Kluber and the Indians visit the division-rival Royals. Max Scherzer is always worth a watch, plus the Rockies and Brewers fight for Wild Card supremacy.
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Here's what to watch for throughout the day (all times in ET):
Heaney returns from Tommy John: LAA@BAL, 7:05 p.m.
Heaney, the ninth overall Draft pick in 2012, was off to a solid career before surgery derailed him. Through 141 innings, he had a 4.09 ERA with 105 strikeouts and 35 walks. Now he's ready to get back on track.
The 26-year-old lefty impressed in his six rehab starts, with 29 strikeouts and five walks in 27 2/3 innings between Rookie ball and Triple-A Salt Lake City.
Heaney will face off against Jeremy Hellickson, who has had mixed results since joining Baltimore from Philly at the Trade Deadline. After throwing seven scoreless innings in his Orioles debut, he has given up six runs in one start and three in the other.
Yankees-Red Sox, Round 5: NYY@BOS, 7:10 p.m.
New York has gotten the better of Boston through 12 games with a 7-5 edge, and the Yankees are 4-2 at Fenway Park. They'll continue their rivalry with a matchup of young lefties Jordan Montgomery and Thomas Pomeranz.
Montgomery pitched well against the Red Sox on Sunday, even after taking a batting-practice ball to the head the day before. He held Boston to one run on two hits with four strikeouts over 5 1/3 innings.
Pomeranz will face the Yankees for a fourth time this season, and the Red Sox won all three of the prior matchups. Still, the Yankees have hit him fairly hard for nine runs (eight earned) over 17 2/3 innings. He's been especially susceptible to the long ball, with a homer allowed in each of those starts.

Kluber looks to tie history: CLE@KC, 8:15 p.m.
Kluber is in the midst of a historic stretch with at least eight strikeouts in 14 straight starts. With one more start, he'll tie Randy Johnson for the Major League record within a season. Johnson has the overall record with 17 straight from September 1999-June 2000.
The division-rival Royals will counter with Ian Kennedy, who has struggled at home this season. In 10 starts at Kauffman Stadium, he owns a 5.43 ERA, compared to a 4.30 mark in 12 road starts.

Friday will also mark the return of All-Star reliever Andrew Miller, who is expected to be activated off the 10-day disabled list.
National League Wild Card showdown: MIL@COL, 8:40 p.m.
The Rockies are neck-and-neck with the D-backs for the first Wild Card spot in the NL, but the Brewers are right behind them. Friday also begins the final series of the year between the teams, making it all the more important.
Milwaukee starter Matt Garza has struggled in his past two starts, with 12 runs (11 earned) and five homers given up in 8 2/3 innings. He'll face off against Rockies rookie German Marquez, who saw his streak of six quality starts snapped after giving up five runs to Miami last time around.

Scherzer takes on the Padres: WSH@SD, 10:10 p.m.
Scherzer is having yet another great season, and he has been especially dominant in his past 15 starts. During that stretch, he has struck out 144 batters in 100 2/3 innings and has a 1.79 ERA. That run began when he held the Padres to one run over 8 2/3 innings with 13 strikeouts.

Luis Perdomo will get the call for the Padres. He has given up at least four runs in five of his past six starts, though he had a quality start against the Nationals in May -- three runs scattered over six innings with six strikeouts.