The France international is training on a daily basis with the rest of the team and gave his side a thumbs up before the crucial continental contest
The 32-year-old has not featured for the club since late February as he is currently awaiting a liver transplant, one year after he underwent surgery to remove a tumour on the organ.
Abidal is still training with his team-mates, though, and just one day before the crunch match against Milan, Dani Alves took a picture with the Frenchman giving a thumbs up for the camera.
"Here we are, preparing for tomorrow," Alves wrote on Twitter. "Let's go, with no fear of being happy."
Abidal, who arrived at Barca in 2007, signed a new contract earlier in the year that will keep him at Camp Nou until 2013.