Giants vs Marlins live stream: Watch online free 10:15 ET Friday for the second of a four-game series in San Francisco.

Henderson Alvarez (2-3, 3.33) will get the ball for the 21-21 Miami Marlins who is 0-3 with a 4.73 ERA over his last five starts on the road dating to last year. His opponent on the mound vs the San Francisco Giants (27-15) will be Yusmeiro Petit (2-1, 4.85 ERA). Watch the free live stream online to see which arm can help lead his team to a victory.

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Alvarez latest start was one of his worst performances of 2014, surrendering a season-high five earned runs and seven hits with three walks in four innings of Sunday's 5-4 loss at San Diego. That was in stark contrast to five days earlier, when the right-hander tossed a six-hitter in a 3-0 win over the New York Mets for his second shutout of the season, according to MLB.com.

"He didn't have a good feel for his sinker and that is his bread and butter," catcher Jeff Mathis said of Alvarez's struggles Sunday. "Without his sinker we were doing what we could do throw the ball over the plate."

Alvarez planned on doing some homework to learn more about Giants hitters during Thursday's series opener.

"I will be keeping the charts for the hitters tonight, and I've seen them play on television," Alvarez said. "I always check them out, how they might attack certain pitches."

Petit was informed about an hour before that game that he would replace Matt Cain for his last start after Cain cut his index finger while making a sandwich. Now he will replace Tim Hudson, who's sidelined by a strained left hip. Petit was given a full-day's notice.

"I'm prepared for it at any time," Petit said of his 45th career start. "Even if it's one moment before the game."