The Brazilian World Footballer of the Year has not played since picking up a leg injury against Benfica in the quarterfinals.

While Ronaldinho's return is a welcome fillip for Barca coach Frank Rijkaard it was tempered by news that Swedish international Frank Larrson would miss the game after picking up an injury in Barca's 1-0 win over Villarreal last Friday.

The Catalan giants are also without precocious teenage winger Lionel Messi, who is returning to Argentina for treatment on his troublesome thigh, and Deco, the only European winner at the Nou Camp, who is suspended for the first leg.

Santi Ezquerro though has been named in Rijkaard's squad despite damaging his right knee against Villarreal.

Barca boss Frank Rijkaard, who also welcomes back Thiago Motta, said: "With the great number of games we've been playing I'm not surprised we've been suffering injuries.

"At times like this every healthy player is a bonus."

The Dutch coach, reflecting on the Villarreal success, added: "It was very important to get a win after the recent draws because now our spirits will be high ahead of meeting Milan."

The two European heavyweights crossed swords in last season's Group stage, with Milan winning 1-0 at home and losing 2-1 to a last-gasp Ronaldinho strike at the Nou Camp.

Ronaldinho remarked: "Any team we're going to face at this stage is going to be very tough but the one advantage is that we know how Milan play.

"Out of all the remaining teams at this stage we've probably got the toughest."

Barca travel to northern Italy in the knowledge that their hosts, six times European champions to their one, have never lost a Champions League semifinal.

"We're going into it with caution but also with hope," said club president Joan Laporta.

Milan too go into the match in high spirits after KOing city rivals Inter by the same scoreline on Friday, a result that gave the Rossoneri renewed hope of catching Serie A leaders Juventus, the goal coming from defender Kakha Kaladze.

Milan coach Carlo Ancelotti will be without tonsillitis-hit Filippo Inzaghi, who has proved instrumental in their charmed run to the last four.

Last year's beaten finalists were two minutes away from going out on the away goals rule to Lyon in the quarters until the striker saved the day with his fourth goal in the past three games.

There are no such fitness concerns surrounding Andriy Shevchenko, who will be itching to add to his European record of 52 goals against the Spaniards.

Milan's journey to the last four took them past Lyon and in the previous round Bayern Munich while Barcelona have marched past Benfica and Chelsea.

Kaladze meanwhile is feeling positive about Tuesday's tie.

"We are improving a lot. We have great consistency, particularly in defence, and must continue on this way because this is the decisive moment of the season," said the Georgian.