Ernesto Valverde depends on Andres Iniesta. Until he knows if he will be available for the Chelsea game, he doesn't know what his team will be. He will wait until the last minute.
The midfielder injured his hamstring on March 4 against Atletico. Barça didn't reveal how long he would be out for although the type of injury would suggest at least 15 days. Between March 4 and March 14 -- the day of the Chelsea game -- just 10 days will have passed. Not enough time, although it wouldn't be the first time Iniesta has shown his commitment to the cause, forcing himself on the pitch despite not being at 100 percent. In any case, even though he knows his own body, the medical team will help with the final decision. There should be no risks. There's a lot of season left.
If Iniesta plays, there are two options and it will depend on the system Valverde prefers: 4-3-3 or 4-4-2. Nine players will start whatever, regardless of Iniesta: Ter Stegen, Sergi Roberto, Piqué, Umtiti, Jordi Alba, Busquets, Rakitic, Messi and Suárez. The other two positions depend on Andres. With a 4-3-3, Dembele would play on the right. That's the most attacking plan. The presence of Ousmane would open the pitch up. But there's also the possibility that even with Iniesta in the side, Valverde picks Paulino, keeping to a 4-4-2 formation.
There's also the possibility that Iniesta can't play -- at least not from the start. Without the captain, the same two positions are still the talking point. If Valverde goes for the more conservative 4-4-2, he could opt for Paulinho and Andre Gomes. In a 4-3-3, he would go with Paulinho in for Iniesta and have Dembele on the right. It would be a side similar to the one which played against Malaga, albeit with Messi in for the cup-tied Coutinho.
They're the four cards Valverde has to play, save any late surprises. And a lot will depend on how Iniesta's recovery goes over the next 48 hours.