Runaway LaLiga champions Real Madrid welcome Real Betis for the last game of the domestic season in what was supposed to be just a dress rehearsal ahead of next week's Champions League final against Borussia Dortmund at Wembley.

But the shock retirement announcement of midfielder Toni Kroos on Tuesday suddenly changed the significance of Saturday's clash, which quickly lost that end-of-the-season vibe.

A sold-out crowd will bid farewell to a fan favourite and all-time club great who will play his final game at the stadium after a remarkable decade with the Spanish giants.

Kroos said in a statement on his social media that his last game for Madrid will be next week's Champions League final, adding that he will retire after this year's European Championship on home soil.

Madrid have had little to play for in the last couple of weeks after claiming a record-extending 36th LaLiga title on May 4 and reaching the Champions League final four days later.

Carlo Ancelotti has rested most of his regular starters in the last three league matches but is expected to use the Betis game as a practice run for the Wembley final, with two big question marks in defence.

Goalkeeper Thibaut Courtois' full recovery from an ACL tear suffered in August has left the Italian with a tricky decision.

Stand-in Andriy Lunin was Real's penalty hero as they beat Manchester City to reach the semi-finals, but Courtois is widely considered one of the best keepers in the world and is likely to regain his starting spot against Dortmund.

The centre-back who will play alongside Antonio Rudiger is Ancelotti's other issue.

He has used holding midfielder Aurelien Tchouameni and long-time back-up defender Nacho alongside Rudiger after David Alaba and Eder Militao sustained ACL tears early in the season.

After making a full recovery last month, Militao has struggled to regain top form and, with Tchouameni out with a foot injury sustained against Bayern Munich, Ancelotti is left to decide between the Brazilian and Spaniard Nacho.

Champions Real Madrid have 94 points, 12 ahead of second-placed Barcelona going into the final round of LaLiga matches this season.