By Pilar Suarez | Goal.com Spain
Barcelona have made a near-perfect start to the season in La Liga, winning seven of their eight games to top the table with 22 points from a possible 24, also coming out on top in their two Champions League games.
It's so far, so good for the Catalans under Tito Vilanova in the two main competitions, but defensive deficiencies and players missing through injury or suspension have given the coach much to think about this term - and Tuesday night's Champions League match at home to Celtic is no different.
Here, Goal.com looks at the dilemmas facing Vilanova in the build-up to the Camp Nou clash with the Scottish champions.
|ALBA OR ADRIANO AT LEFT-BACK?
Jordi Alba scored his first goal for Barcelona in Saturday night's epic encounter at Deportivo La Coruna, which the Catalans won 5-4. but the Spain defender also put through his own net in spectacular style at Riazor as he inadvertently lobbed Victor Valdes late in the game.
The former Valencia full-back is adapting well to life back at Camp Nou, where he came through the youth ranks, but Vilanova has preferred Adriano at times on the left this term and either could start on Tuesday.
So with Barcelona at home and likely to have much more of the possession than Celtic, the coach must decide whether to select Alba or the more attacking Brazilian - especially as Dani Alves remains sidelined on the opposite flank.
|WHO STANDS IN FOR BUSQUETS?
Sergio Busquets is suspended after his red card against Benfica in the last matchday and that causes a headache for Vilanova. Javier Mascherano and Alex Song are able to play in the defensive midfield role, but both may be needed in central defence and the Cameroonian is still adapting to life at Camp Nou.
Another alternative for Vilanova is to retain Cesc Fabregas in midfield, after the former Arsenal captain starred against Deportivo, and begin Tuesday's game with the Spain star in an attacking triumvirate alongside both Xavi and Andres Iniesta.
Vilanova has options, but Barca rarely play without the Spain midfielder in front of the defence these days and it will be interesting to see how the Catalans adjust on Tuesday.
|MONTOYA OR THREE AT THE BACK?
With Alves still sidelined, Martin Montoya could be in line for another appearance at right-back on Tuesday. The La Masia graduate has featured several times since the Brazilian's injury and offers the Catalans a good offensive outlet down the right.
However, with problems in central defence and doubts in defensive midfield, Vilanova could opt to select three at the back against Celtic, as Pep Guardiola's side did at times last season. And if Tito's team start with a 3-4-3, Montoya will almost certainly miss out.
If he is picked, however, he is likely to be paired on the right with Pedro. Both players get up and down the pitch with great effect and can continue what has looked a promising partnership on Tuesday.
|RISK RECALLING PIQUE?
Carles Puyol is definitely out, but Gerard Pique had been expected to return in time for this match. However, there are now doubts over the Catalan defender's participation on Tuesday as he struggles to shake off a foot problem.
If Pique misses out, Mascherano is set to be partnered at the back by either Song or Adriano - and perhaps even both men if Vilanova opts for a three-man back line on Tuesday.
Youngster Marc Bartra is another possibility, although he has yet to be used this term - even with many players missing in defence.
|WHO WILL JOIN MESSI IN ATTACK?
Lionel Messi scored a brilliant hat-trick against Deportivo on Saturday and now has 15 goals for the Catalan club this term. The Argentine will relish this fixture, having suffered a serious injury against Celtic in 2008. But who should join him in attack?
David Villa was handed only his second start of the season on Saturday, but was sacrificed following Mascherano's red card. The striker seems set to start on the bench this time after Pedro played just 34 minutes at the end of the Deportivo game and Alexis Sanchez was given the weekend off altogether after international week.
Cristian Tello's raw pace is another alternative on either side. The youngster played 56 minutes against Deportivo, scored his side's second goal and should still be fresh for Tuesday's clash.