Diego Costa joining Atletico side with plenty of competition in it - Filipe Luis

Atletico Madrid full-back Filipe Luis says that Diego Costa is coming back into a squad full of competition for places.

After a long summer of uncertainty, mostly spent on holiday back home in Brazil, Costa attended Atletico's 2-0 La Liga win over Sevilla on Saturday and was at the club's training ground on Sunday, although his return for a reported €58 million fee from Chelsea has yet to be confirmed.

When the Spain international is available to play for Atletico from January -- after the club's transfer ban ends -- he will join fellow new boy Vitolo, Antoine Griezmann, Angel Correa, Yannick Carrasco, Luciano Vietto and Fernando Torres as attacking options for Diego Simeone.

Simeone has been rotating heavily through the early weeks of the season and made five changes last weekend, including resting Diego Godin, who should return for Wednesday's Champions League game at home to Chelsea.

Speaking to Marca after the Sevilla victory, Filipe Luis said that "nobody is a certain starter" given the range of options Simeone now has within his squad.

"Last year there was also rotation," he said. "There was almost never a fixed first XI. It depends on the opponent and their characteristics. The important thing is everyone knows they have a chance to play, nobody is a certain starter. It is the team which wins.

"It is not easy, but everyone understands this. It is impossible to compare [our squad] with [Real] Madrid and Barcelona, we do not have the same characteristics. But we do have a competitive and diverse squad."

Ahead of Chelsea's visit, Simeone's side are up to second in the La Liga table, unbeaten in all competitions so far this term, having conceded just once in their last five outings.

"The team is in a very good moment, physically and mentally," Filipe Luis said. "There is enormous confidence, we know each other well, we have been together a long time and we enjoy playing football, which is the most difficult. We must keep going on this path, difficulties will come, but we must not lose our focus."

Filipe Luis said Costa had made a big "effort" to rejoin the club from Chelsea this summer, with the La Liga side also straining to bring back a player the full-back rates among "the top three forwards in the world."

"I spoke with him during the summer," Filipe Luis said. "Few people have made the effort he did to come to Atletico and be happy here. The club made an immense effort, and it is an important step as he is among the best three forwards in the world.

"He was winning trophies where he was, he is ambitious and that is contagious for the whole team. He gives us strength, even if he will not be able to play for a while."