BARCELONA: Barcelona coach Luis Enrique is concerned that Wednesday's Copa del Rey match against Athletic Bilbao could wear down his team ahead of its critical Spanish league game against Atletico Madrid.

Barcelona holds a 2-1 advantage when it hosts Bilbao in the second leg of the quarterfinals.

On the same night in the capital, Atletico will also seek its spot in the semifinals when it plays Celta Vigo after their scoreless first leg.

Three days later, Atletico will travel to Camp Nou trailing Barcelona on goal difference at the top of the Spanish league standings.

"The only game key to reaching the Copa semifinals is tomorrow's, who knows what will happen with the rest," Luis Enrique said. "I am worried about the physical wear and tear taking into account that Atletico is coming on Saturday.

My team is fine, but these are both very intense matches."

Neymar returned to team training on Tuesday after muscle pain forced him to miss Barcelona's last game. But fever may sideline midfielders Andres Iniesta, Sergio Busquets and Arda Turan after all sat out of training.

Thursday's quarterfinals will feature Valencia needing to turn around a 1-1 draw when it visits Las Palmas in the Canary Islands, while Sevilla takes a 2-0 advantage to second-division club Mirandes.

Here are some things to know about this week's Copa del Rey matches:

CHASING PEP

Barcelona is closing in on a club record set by former coach Pep Guardiola, who kept the team undefeated for 28 consecutive games in the 2010-11 season.

After a stellar debut season that ended with the team matching Guardiola's rare treble of Champions League, Spanish league and Copa del Rey titles, Luis Enrique has guided his team to 24 games without a loss.

Barcelona will look to make good on first-leg goals by Neymar and Munir El Haddadi, who scored before Aritz Aduriz gave the Basque club a lifeline.

Lionel Messi missed the opening leg because of muscle pain, but returned to score the winning goal in Saturday's 2-1 victory at Malaga in the league.

FIFTEEN YEARS

Only Barcelona, with 27 cups, can boast more success in the competition than Bilbao, which has won the tournament 23 times.

But Bilbao faces a daunting challenge at a stadium where it hasn't won since November 2001.

Barcelona is unbeaten in all 17 home games this season and routed Bilbao 6-0 at Camp Nou in the league less than two weeks ago.

Ernesto Valverde's team can cling to its upset of Barcelona in the Spanish Super Cup to start the season, when it secured a 1-1 away draw after stunning the European champions 4-0 at San Mames.

SQUEAKY CLEAN

A draw with goals would suffice for Celta to eliminate Atletico, but Diego Simeone's team is expert at keeping a clean sheet.

Atletico hasn't conceded a goal in five straight matches and has only allowed one in its last nine games.

While Jan Oblak has emerged as the league's top goalkeeper, Miguel Moya has been Simeone's pick for the Copa del Rey, where he has let two goals past him in five outings.

NEVILLE'S HOPE

Gary Neville's coaching career has gotten off to a rocky start.

Since the former Manchester United defender took over in December, Valencia has been eliminated from the Champions League and has yet to win in seven Spanish league matches.

But the Copa del Rey has been another story, where it won three straight until last week's slip at home against Las Palmas.

In 11th place and 16 points from the Champions League positions, Valencia's only shot at salvaging the season is in the cup.

"The wins will come," Neville said after a 1-1 draw at Deportivo La Coruna on Sunday. "The fans want victories and I am desperate to give them to them."