A non-roster invitee who claimed a spot on the Opening Day roster last season, Slowey needed just 25 pitches (20 strikes) to retire six of the seven hitters he faced. He struck out four, including the side in the second.
Lannan, following knee surgery and a down year in 2013, countered Slowey with two scoreless innings of his own. He struck out three -- each swinging -- and allowed just a one-out double in the second, to Derek Dietrich. Of his 26 pitches, 19 were strikes, and he threw first-pitch strikes to the first six batters.
With the score knotted at 1 in the fifth, Miami scored the go-ahead run by taking advantage of a lack of command by non-roster invitee John Church.
Rob Brantly started the inning with a single, moved to second on a wild pitch and advanced to third on Ed Lucas' groundout to first. Church, who went 3-4 with a 3.34 ERA over two Minor League levels last season, hit Austin Barnes with a pitch to put runners on the corners. Ball four to the next batter, Jake Marisnick, trickled away, allowing Brantly to race in.
The Marlins produced a five-run sixth against lefty Josh Edgin with a pair of two-run singles by non-roster invitee Reed Johnson and Barnes. Brent Keys tacked on an RBI.
Barnes, a prospect who split time between Class A Jupiter and Double-A Jacksonville last season, blasted a solo homer to left off righty Kyle Farnsworth to give the Marlins a 1-0 lead with one out in the third.
Farnsworth, who signed a Minor League contract with the Mets this offseason and is in contention for a bullpen role, escaped further damage with two runners on with the help of a caught stealing.
Lucas Duda knocked a one-out solo shot to right against righty Arquimedes Caminero in the fourth.
Duda finished 1-for-3 for the second straight day after hitting a double in the Grapefruit League opener as he and Ike Davis compete for the starting job at first base.
Lefty Scott Rice, a feel-good story during a breakthrough 2013 season, pitched a perfect fourth with a strikeout of Dietrich. Rice spent 13 years between the Minor and independent leagues before earning a spot on the Opening Day roster. He made 73 appearances, going 4-5 with a 3.71 ERA. His season ended prematurely, however, when he had surgery for a sports hernia.
Up next: Left-hander Brad Hand is getting the start against the Nationals on Sunday at Viera, Fla., at 1:05 p.m. ET. Washington will start Doug Fister in his Grapefruit League debut. Henderson Alvarez had been set to make this start but is being skipped due to an infection in his right shin. This is a crucial Spring Training for Hand, who is out of options, so he must make the Opening Day roster or risk being lost by the organization.