The two 23-year old pitchers will square off Wednesday night as the Miami Marlins host the New York Mets.Alvarez (1-1, 2.64 ERA), who didn't make his season debut for the Marlins until July 4 due to right shoulder inflammation, has been much better lately after posting a 4.58 ERA in his first three starts. The right-hander has held opposing batters to a .159 batting average over 13 scoreless innings in his past two outings.That included six innings of two-hit ball in a 2-0 win over Pittsburgh on Friday to pick up his first win with Miami."He just had explosive stuff," Pirates catcher Russell Martin said. "His fastball was electric."Alvarez has seemingly been helped by his offseason trade from Toronto, where he allowed 1.39 home runs per nine innings, the ninth-worst total in the majors, while pitching in one of the league's most hitter-friendly parks. With Miami, where the Marlins (40-65) play in one of the toughest venues to hit a home run at, Alvarez has yet to surrender a home run in 30 2/3 innings.He'll face off against Mejia (1-0, 0.00), who followed brief stints with the Mets (48-56) in 2010 and 2012 with an excellent season debut Friday. Mejia limited Washington to seven hits and struck out a career-high seven in seven innings of an 11-0 win."I haven't seen him obviously that good in a long time," manager Terry Collins said. "The command of his stuff was very, very good. His location. I thought he pitched an outstanding game. His best changeup. I didn't know he had one. He used it and used it effectively."While avoiding the home run has made the difference for Alvarez, avoiding the walk has been key for Mejia. The right-hander walked 29 in his first 55 innings in the big leagues, but walked no one Friday.Mejia's strong start was only the latest in a stretch that spans back to Double-A Binghamton, where he allowed a run and six hits in 11 innings.Mejia isn't the only Met to enjoy a strong July. John Buck, after singling home the two go-ahead runs in New York's 4-2, 10-inning win over Miami on Tuesday, has 16 RBIs this month, surpassing his combined total from May and June. The catcher is batting .302 since July 6.On Tuesday, he was able to deliver after failing to drive a runner in from third with one out in the eighth."When I came up I kind of had a similar situation with (Miami reliever Steve) Cishek, who is more funky, I said, 'All right, just stick with that approach,'" Buck said. "He left it over the plate and I got the results I wanted this time."He was joined by Juan Lagares, who went 3 for 3 with a triple and a walk Tuesday. Lagares, who entered June with a .149 average, is batting .319 since with 16 of his 43 hits going for extra bases.Alvarez, who has received 10 runs of support over his first five starts, hopes the Marlins can break out after averaging 2.4 runs per game while losing eight of 13.He'll look to avenge his only start against the Mets on May 20, 2012, when he allowed six runs in five innings of a 6-5 loss.