Argentine Martino, who took over from the ailing Tito Vilanova last month, told a news conference on Saturday it was their turn to have a rest after their exertions in Wednesday's Spanish Super Cup triumph against Atletico Madrid.
Barca's World Player of the Year Lionel Messi, who missed last weekend's 1-0 La Liga win at Malaga with a bruised thigh, came through a full training session on Saturday, while full-back Adriano has been given the all-clear by medical staff, the club said on their website.
Barca top the La Liga standings on goal difference after winning their opening two matches but still have plenty of room for improvement, Martino said.
"What the team needs is to improve its teamwork and that will help improve individual players," he told reporters at Barca's training facility outside the Catalan capital.
"How do we improve that? Working in training, coordinating movement with the fullbacks and the central players. We have to harmonise our movement."
Barca have conceded only one goal in four competitive games this term but against Malaga and Atletico struggled to create clear chances.
"It is positive that they are not scoring against us and we have not allowed many scoring opportunities," Martino said.
"It's also true that we have to score more goals from the forward line," he added.
Andres Iniesta or Cesc Fabregas are likely to fill in for Xavi in central midfield on Sunday, with Pedro joining Messi and new signing Neymar in a three-pronged attack.