MADRID (AP) -- After its first loss of the Spanish league season, Barcelona coach Luis Enrique is focusing on two areas in clear need of improvement -- a surprising lack of scoring power and a defense that's leaking goals.
The club's 4-1 defeat against Celta Vigo on Wednesday was its worst in the league since losing by the same score at Real Madrid in May 2008 when Frank Rijkaard was in charge.
However, Barcelona had already received a warning this season when it fell 4-0 at Athletic Bilbao in the first leg of the Spanish Super Cup, which it lost 5-1 on aggregate.
Now, Barcelona hosts promoted Las Palmas -- which won its first match against a struggling Sevilla -- and will hope its attacking trio of Lionel Messi, Neymar and Luis Suarez find their rhythm -- and the target.
"Our problem is that in the first games of this season we have been struggling to turn chances into goals," Luis Enrique said.
Real Madrid heads into round six aiming to maintain its spot as league leader when it hosts Malaga, while Celta Vigo is level on points at the top before traveling to seventh-place Eibar.
Here are some things to look out for in this weekend's matches:
Unlike Barcelona, Madrid isn't having any problems at all finding the net, with Cristiano Ronaldo and Karim Benzema having scored five league goals each.
After Madrid's 2-1 win at Athletic, where Benzema scored both goals, coach Rafa Benitez called the France striker a "very great" player.
"He's a different kind of striker, not confined to the area," Benitez said. "He moves around a lot, possesses quality and has a very good understanding with Cristiano Ronaldo," he said. "I've asked him to score 25 goals this season."
What is more surprising is that Celta's 28-year-old Manuel "Nolito" Agudo has been averaging a goal a game to equal Madrid's expensive duo.
Luis Enrique had no problem acknowledging how well Celta played, and even warned his squad they might get run over by a team playing at "200 kilometers per hour."
The Barcelona coach knew what the players from the rainswept northwest of Spain were capable as he was in charge there in his previous job.
"We tried to create problems, but suffered a lot in one-on-one situations," Luis Enrique said. "When a team has played better than you, there is nothing much that you can say."
Celta will hope to capitalize on its winning momentum, but it travels 700 kilometers (435 miles) east to Basque club Eibar, which conceded a goal in the last minute of injury time to give Levante a 1-1 draw in the last round.
Villarreal has yet to lose a match and also has 13 points to sit alongside Madrid and Celta, but it will have a tough match when it hosts Atletico Madrid on Saturday.
Atletico has one point less, having lost 2-1 to Barcelona in round three, but coach Diego Simeone will be eager to unleash in-form forward Antoine Griezmann, who scored both goals in his team's 2-0 win against Getafe.
One of the surprises this season is how Unai Emery's Sevilla has been unable to rise above the relegation zone.
After its fifth consecutive loss on Wednesday, Canary Island-born midfielder Victor "Vitolo" Machin said his team has repeatedly said it needed to win its next match.
"Now we really need to make that happen," he said.
It hosts Madrid side Rayo Vallecano, which is coming off a 2-1 win over Sporting Gijon.