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.
Real Madrid 4 Bayern 2 player ratings
Real Madrid 4 Bayern 2 player ratings
1/22 Keylor Navas – 6 out of 10
Found wanting when called upon. Should have done better to prevent Ramos’ own goal.
2/22 Dani Carvajal – 7 out of 10
His early effort from range may not have gone in but it set the tone for Madrid to have the better of the first half.
3/22 Nacho – 7 out of 10
More solid than his defensive partner, and looks to be benefitting from gaining Zinedine Zidane's confidence.
4/22 Sergio Ramos – 6 out of 10
Unfortunate to divert the ball into his own net, but it could have been avoided with a little more communication.
5/22 Marcelo – 9 out of 10
Excellent. Superbly blocked Thiago’s effort early on, then produced a brilliant goal-line clearance after the break to deny Robben. Impressed going forward too, setting up Ronaldo in extra time.
6/22 Luka Modric – 7 out of 10
Key to Madrid’s excellent spells of first half build-up. Ronaldo should have rewarded one particularly special pass with the goal it deserved.
7/22 Casemiro – 7 out of 10
Careless in his challenge on Robben for the penalty. Otherwise, a solid presence disrupting Bayern’s forays forward.
8/22 Toni Kroos – 5 out of 10
Struggled to match the influence of his fellow midfielder Modric.
9/22 Isco – 6 out of 10
Failed to build on Saturday’s excellent showing at Sporting.
10/22 Karim Benzema – 5 out of 10
Offered very little before being hauled off for the more impactful Asensio.
11/22 Cristiano Ronaldo – 8 out of 10
A quiet start but then came another ‘clutch’ goal, just like his two in Bavaria. Two more followed thanks to poor officiating, but this was still a reminder that you should never write Ronaldo off.
12/22 Manuel Neuer – 6 out of 10
Will be disappointed to have conceded six over the two legs, but was outdone by some poor officiating here.
13/22 Philip Lahm – 6 out of 10
Struggled to cope with Marcelo, who got the better of him too often. We have come to expect more.
14/22 Jerome Boateng – 7 out of 10
Heroic block on the line stopped Ramos from putting the hosts in front in the first half.
15/22 Mats Hummels – 8 out of 10
Another defender who put his body on the line when it counted. Spectacularly blocked Kroos’ shot in the first half.
16/22 David Alaba – 5 out of 10
His poor crossing let his teammates down when they were making headway early on.
17/22 Xabi Alonso – 5 out of 10
Surprisingly poor in possession during his last Champions League appearance, with several wayward passes. Replaced by Thomas Muller deep into the second half.
18/22 Arjen Robben – 8 out of 10
Made things tick in Bayern’s attack. Questionable role in the penalty, maybe, but his side's stand-out performer still.
19/22 Arturo Vidal – 4 out of 10
His tackle was fair and should not have resulted in a red, but still, too often a liability. Should also have done better when slipped in by Robben soon after Bayern’s first goal.
20/22 Thiago – 5 out of 10
Off the pace in the opening stages and failed to grow into the game.
21/22 Franck Ribery – 5 out of 10
A fading force, unfortunately. Simply did not trouble Madrid’s backline with the regularity of Robben. Withdrawn for Diego Costa.
22/22 Robert Lewandowski – 6 out of 10
Not his best night, despite cooly converting the penalty.
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.