Barcelona midfielder Sergio Busquets says he is prepared to play in central defence if needed as Barca look to move one step closer to the Primera Liga title with a win at Real Zaragoza tomorrow. The Catalans progressed to the semi-finals of the Champions League for a record sixth consecutive season on Wednesday night as they eliminated Paris Saint-Germain on away goals. But they suffered another injury blow in defence as Adriano, who had just returned from a hamstring injury, was carried off during the second half. With Carles Puyol and Javier Mascherano already sidelined, playing the inexperienced Marc Bartra or moving Busquets back into the centre of the defence appear to be the only two options available to coach Tito Vilanova, and the Spanish international insists that he would be comfortable in the back four. "If I need to play at centre-back, I will do whatever is necessary for the team," Busquets told Barca TV. "We still have two league games before the semi-finals of the Champions League. If we can pick up six points in these two games in the league, we will take a huge step towards winning the title." The Catalans were far from their best in midweek as they struggled without their talisman Lionel Messi, who started the game on the bench to protect a hamstring injury. Messi, though, was required to turn the tie in Barca's favour in the second half, as he came on to help set up Pedro's goal, which took Vilanova's men through. And with Messi likely to be rested tomorrow, given Barca's 13-point advantage at the top of the table, Busquets admitted that the Argentine's presence will be sorely missed. "It is clear that Messi is the best player in the world, and when he is not there, you notice it," Busquets said. Zaragoza, meanwhile, are desperate for the three points after a horrendous run of 14 games without a victory that has left them just one point above the relegation zone. However, midfielder Victor Rodriguez believes they can take heart from their 1-1 draw against Real Madrid two weeks ago when they welcome the league leaders to La Romareda. "You can't play the same way against Real Madrid and Barcelona because they play completely differently, but we need to play with the same attitude," said the 23-year-old former Barca youth-team player. Victor welcomed the fact that Messi is unlikely to be in the Barca squad and said gaining a positive result would be key for momentum heading into their huge relegation clash with Celta Vigo next weekend. "It is a relief for everyone if Messi doesn't play because he is one of the best in the world," he said. "We need to take advantage of our chances and come out of the game with a good taste in our mouth to then go to Vigo with confidence." Real Madrid face a tricky trip to Athletic Bilbao tomorrow, looking to extend their three-point gap over third-placed Atletico Madrid. Jose Mourinho is expected to rotate his side after Real Madrid's exertions in also reaching the Champions League semi-finals, with a 5-3 aggregate win over Galatasaray, despite losing the second leg 3-2 in Istanbul on Tuesday.