The teams have split the first two contests with Arizona winning 5-3 on Tuesday, due in large part to John Ryan Murphy's three RBIs.
Meanwhile, Ray (2-0, 4.88 ERA) is off to a slow start compared to his breakout year of 2017, when he went 15-5 with a 2.89 ERA, making the All-Star Game for the first time. He also finished seventh in the Cy Young voting.
On Wednesday, he will make his first start since April 29, when he was sidelined by a strained right oblique.
"I feel ready for this," Ray told mlb.com. "I feel like I'm in really good shape. My arm feels good. My oblique is fine. I want to pitch and give us a chance to win."
Ray, who averaged 30 starts in each of the past two years, will be making only his seventh appearance of 2018. He won his first two starts and then had four no-decisions and lasted just 1 1/3 innings on the night of his injury.
He has only two quality starts this year and was going to make a rehab appearance Monday night at Triple-A Las Vegas when the Diamondbacks coaches called him to tell him to come to South Florida instead.
Two rehab starts, Ray said, were enough.
"My first (rehab) start was rough," he said. "After not pitching for eight weeks, there was some rust to knock off. But that second start, I felt good. All my pitches were working in all four quadrants, up, down, in and out."
Ray, who has averaged 93 mph this year on his fastball, made his major league debut in 2014 and has improved his strikeout rate per nine innings in every season (6.0, 8.4, 11.3, 12.1).
So far this season, Ray has improved in that stat again, striking out 14.6 batters per nine, which would lead all major league starters if he had enough innings to qualify.
Part of the strikeout formula for Ray, which began last year, is using his curve more, adding one more plus pitch to go with his fastball and slider.
On Wednesday, however, the Diamondbacks will be careful with Ray, not wanting to push him for too many innings in his first game off the DL.
"We're just going to see how each inning goes," Arizona manager Torey Lovullo said. "We will make adjustments from there."
Ray is 1-2 with a 3.06 ERA in three career starts versus Miami.
Meanwhile, the Marlins will counter with their own left-hander, Wei-Yin Chen (2-4, 6.70 ERA), who has been a major disappointment for Miami ever since signing a five-year, $80 million contract prior to the 2016 season.
Chen, who has mediocre velocity with an average of 90.5 mph on his fastball, is 9-10 in his time with the Marlins.
The Marlins are 5-6 this year when Chen starts. Chen has managed only two quality starts this year.
Chen, who turns 33 next month, is averaging 6.5 strikeouts per nine, which is the worst mark of his career. His 4.5 walks are also on track to be a career worst.
In other news, the Marlins on Wednesday will get back manager Don Mattingly, who served a one-game league suspension Tuesday. Miami's Dan Straily was also suspended, as the pitcher and his manager were faulted for their roles in a beanball war that broke out against the San Francisco Giants on June 19.
The Marlins are also expecting the return of catcher and All-Star candidate J.T. Realmuto, who missed the previous two starts after being hit with a foul ball while squatting behind the plate.
Realmuto, who is hitting .308 with 18 doubles, three triples, 10 home runs, 32 RBIs and a .916 OPS, was struck on his left wrist.
"He's got a lot more range of motion now," Mattingly told The Miami Herald. "The X-rays were negative, but we want to get the swelling and the soreness out of there."