The 27-year-old was brought off during the second half of Madrid’s quarter-final first leg win at Bayern Munich last week with a calf problem.
Bale subsequently missed the dramatic late win over Sporting Gijon at the weekend and the return leg against Bayern, which Madrid won 4-2 after extra time.
The Wales international has, however, stepped up his recovery and trained with his fellow first-team players on Thursday.
A statement on the club’s official website read: “Zidane's squad carried out their first training session since qualifying for the Champions League semi-finals and now turn their attention to the game against Barcelona
“Bale rejoined the group, in a session in which the starting eleven from Tuesday's game carried out drills using the ball, before training using the indoor facilities.”
Toni Kroos and Dani Carvajal are also in line to play against Barcelona, despite picking up minor muscle problems in this week’s win over Bayern.
The pair both trained with the other members of Madrid’s starting XI from Tuesday’s victory.
Madrid currently sit three points clear at the top of La Liga with a game in hand over Barcelona, who will go into the game reeling from their Champions League elimination.
A Madrid win will see Zidane’s side move six points clear with six games left to play, including a trip to play Tony Adams’ relegation-threatened Granada.