Also, Jose Fernandez will make his second rehab start on Friday for Class A Advanced Jupiter as he continues his comeback from Tommy John surgery, while Henderson Alvarez -- on the 15-day DL since May 23 with right shoulder inflammation -- has begun throwing again.
"We know it's going to take pitching to get us where we want to go," Jennings said prior to Thursday's series opener against the Rockies at Marlins Park. "We know these guys are close to being back and ready to go, and hopefully they'll be a factor and put us in positions to win."
Latos (1-4, 6.12 ERA) went to the 15-day DL with left knee inflammation on May 23. He made a rehab start for Triple-A New Orleans on Monday, throwing 99 pitches in 4 2/3 innings with no issues.
"Hopefully this little DL stint will kind of strengthen everything and make sure that I'm able to go deep into ballgames," Latos said. "Going 5 2/3 or five innings is not what I like to do. ... Just getting back into a rhythm is going to be the main thing."
Cosart (1-3, 4.08 ERA) is making his second rehab start, as he threw five innings (six runs, six hits, three walks) in an extended spring game on Saturday.
"If it goes well, hopefully it's the last one," Jennings said.
Fernandez pitched on Saturday as well, throwing 54 pitches in three innings for Jupiter. Jennings said he wants to see progress in Friday's start from Fernandez, who allowed five runs and topped out at 99 mph in his first outing.
"Jose has shown progression, and so far he's passed his first test," the manager said. "We'll evaluate after every appearance and get a true read on where he is pitch-wise and how we feel."
Alvarez, who took Fernandez's spot as the Marlins' Opening Day starter, has made just four appearances this season and is 0-4 with a 6.45 ERA. Jennings said the right shoulder inflammation that sent him to the DL has progressed well.
"Alvarez is starting to play catch now up to 60 feet, so that's a positive," Jennings said. "Now he'll start to stretch [his arm] out and build up strength."