Iniesta has not played a full game for Spain since February 2009
Midfielder Andres Iniesta is fit for Spain's opening World Cup match against Switzerland on Wednesday after shaking off a leg injury.
Boss Vicente del Bosque says all 23 of his players, including Fernando Torres and Cesc Fabregas, are available.
"It is a good day for us, because I have 23 players in perfect condition," Spain coach Del Bosque said.
"Iniesta trained well and we will talk to the doctors and decide what is best. We are ready to start this World Cup."
Barcelona's Iniesta, who missed the end of the La Liga season because of a thigh injury, was forced off during Spain's 6-0 friendly victory over Poland last Tuesday.
He returned to play a full part in training on both Sunday and Monday and is now likely to start on the bench against Switzerland.
Del Bosque suggested he would not risk starting Iniesta, saying: "We're thinking about tomorrow [Wednesday], but are also mindful that we have a chance to go forward in this competition."
Liverpool striker Torres, who is recovering from a right leg injury, is also likely to be a substitute, with David Villa starting as a lone striker in front of a five-man midfield of Fabregas, Xavi, Xabi Alonso, David Silva and Sergio Busquets.
Real Madrid's Alonso, who has a slight leg muscle tear and withdrew 15 minutes before the end of Saturday's training session as a precaution, also returned on Sunday.
Spain, the reigning European champions, start the World Cup as favourites, a tag which Del Bosque is wary of.
"It's difficult to get away from the view of the outside, but there is an optimism as if we were going to play the World Cup final now," he added.
"Fortunately, we have players that are aware of the reality and not of utopia. Players that know what football is like."
Spain were the last team to arrive in South Africa, having only jetted in on Friday.
Spain has a team of the century -they have incredible talents, an enormous selection of skilful players
Switzerland coach Ottmar Hitzfeld described Spain as the "team of the century", but told his players that Wednesday's match represented a great opportunity for them.
"Spain are one of the favourites to win the title but we have nothing to lose, this is great opportunity for us," the German said.
"We could be one of the teams that could make one of the favourites tumble, the probability is there.
"Every player of the Swiss team has an opportunity to showcase his talent. At one point we are going to beat Spain. Why not tomorrow?"
But he added that Spain were justified as favourites for the tournament.
"Spain has a team of the century," he said. "They have incredible talents, an enormous selection of skilful players.
"They are very compact, they can focus on attack, but are virtually perfect at the defensive end.
"They just don't focus on scoring goals but also on being organised in every line."