JUPITER, Fla. -- Marlins top prospect Sixto Sánchez's much-anticipated Grapefruit League debut should come sometime next week, according to manager Don Mattingly.

Sánchez, who was delayed getting to camp from the Dominican Republic because of visa issues, also had a false COVID-19 positive test that set him back a couple of days waiting for results. He returned to camp on Saturday.

"We're happy it was just a false positive, but it did set his program [back] just a little bit," Mattingly said during a Zoom call on Saturday. "So I think he's got a 'pen [on Sunday], he'll probably get a live [batting practice] a few days after that. And I would say next week should be fair to get him into the game, so we'll see him in game action."

The 22-year-old right-hander, who made seven regular-season starts as a rookie in 2020, entered Spring Training projected to make the Opening Day rotation. The Marlins are beginning to see pitchers go through their second turn of action on the mound.

After Saturday's 5-3 rain-shortened loss to the Nationals at Roger Dean Chevrolet Stadium, Miami has 18 Spring Training games remaining, with camp set to break on March 28 and Opening Day scheduled for April 1. The club will have early off-days on April 4 and April 9, so MLB Pipeline's No. 15 overall prospect has time to build up. The Marlins also could go with a four-man rotation to open the season.

"I think this year has been better for us," said Mattingly, whose Marlins had eased in Sánchez in the past. "We were able to see his 'pens in the offseason. His offseason program was probably better than it was in the past. I talked about him the other day. I know [pitching coach Mel Stottlemyre Jr.] had video of a number of 'pens, was able to have conversations with [Sánchez] after those 'pens. So it's just been different, knowing that where he's at in his development. But [I] felt like he did a better job [with] his work in the offseason and being prepared for camp to get ready for a season."

Latest on Cabrera

Edward Cabrera, MLB Pipeline's No. 68 overall prospect, still has not begun a throwing program. The 22-year-old right-hander, who was diagnosed with an inflamed nerve in his right biceps, originally felt the discomfort while home in the Dominican Republic before reporting to camp.

"That's just going to be a process of us getting on top of that," Mattingly said. "He's doing better. There has been improvement. But obviously, there was a time in the Dominican where he wasn't throwing, and he hasn't got to the point where we're starting a throwing program yet. So he is improving, but it's going to be a process. I think what we talked about earlier with him, we're not going to take any chances. We know how important this guy's going to be to our future. Once he gets cleared to go start throwing, that's when we start building that."

With the Triple-A season pushed back to May 4, there is no need to rush Cabrera, who had an outside shot at making the Opening Day rotation. Fellow prospects Trevor Rogers, Braxton Garrett, Nick Neidert and Daniel Castano have been part of the audition process.

Others yet to debut

• Reliever Dylan Floro, whom the Marlins acquired in an offseason trade with the Dodgers, has not appeared in a Grapefruit League game.

"Dylan had just a little bit of soreness, and we wanted to make sure we got him back on track, and he is," Mattingly said. "I think he had another 'pen -- it might even be today. Threw one the other day. It was really good after that. So I think he's got one more 'pen in, and then I think we'll get him on that schedule to get outside on the games."

Miami hopes to use Floro in high-leverage situations, along with Anthony Bass and Yimi García. The 30-year-old Floro pitched in 25 regular-season games with the Dodgers in 2020, with an additional six outings in the postseason (three in the World Series).

• Miami's No. 17 prospect, Jerar Encarnación, who was delayed a few days due to visa issues coming from the Dominican Republic, has yet to appear in a Grapefruit League game. The 23-year-old outfielder did face Max Meyer in live batting practice on Saturday.

"Once we got him back in camp, we wanted to give him a few days to be able to kind of get his feet underneath him and get ready, but that has been cleared at this point," Mattingly said.

Alcantara's encore

Marlins projected Opening Day starter Sandy Alcantara didn't attack the strike zone as much as in his spring debut, allowing two unearned runs on two hits with two walks and six strikeouts across 2 1/3 innings. One of those free passes came around to score on Saturday. Of his 48 pitches, 25 went for strikes. In the two-run first, the right-hander threw 27 pitches.

According to Statcast, Alcantara used his four-seam fastball most in the outing (42 percent), followed by his sinker (27%). In 2020, he turned to his sinker 34.8 percent of the time and his four-seamer 24.8 percent. On Saturday, Alcantara reached a maximum velocity of 96.9 mph, with a 95.2 mph average on his sinker. Last season, the pitch averaged 96.2 mph.

"I've got to use more my four-seamer," Alcantara said during a Zoom call. "I think that's my best pitch right now."

Highlights from the game

• Garrett Cooper hit a two-run homer -- his first of the spring -- in the third inning against Nationals late-inning reliever Daniel Hudson, who tried coming up and in with a fastball after setting up a slider away.

"I kind of had a feeling he was going to come back up and in," Cooper said during a Zoom call. "I think I spent a lot of time this offseason working on that, that specific zone, that up and in pitch to get my hands where I want them to be. I hit the ball really well down and in last year, so it's nice to see your work from the offseason translated to a game this early."

• Jazz Chisholm, in competition for the second-base job, made an impressive play to end the fourth.

Worth noting

Veteran southpaw Gio González, who signed a Minor League deal with an invitation to big league camp on Thursday, threw his first bullpen session with the club on Saturday.

Up next

Pablo López will make his second spring start at 1:10 p.m. ET on Sunday at Clover Park against the Mets. The game can be streamed live on MLB.TV.