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After a low-key start to Sunday's (AEST) contest, a Saul Niguez header just before the hour mark put the hosts in front.

Two Atleti substitutes played a part in the second as Diego Costa converted a penalty won by Marcos Llorente to wrap up what ultimately proved to be a comfortable victory for Diego Simeone's side.

Joselu scored a stoppage-time penalty for the visitors, but Atletico is now four points clear of Sevilla in fourth and has opened up a superb nine-point cushion over Getafe in fifth.

Alvaro Morata sent an early header just wide, shortly before his flick-on to fellow forward Joao Felix saw the Portugal international send an impressive acrobatic effort narrowly off target.

Jose Maria Gimenez put a free header over from 12 yards and, despite its opponent defending deeply, it was Atletico goalkeeper Jan Oblak who had the only first-half save to make from Aleix Vidal.

Diego Simeone brought on Costa and Llorente early in the second half as he attempted to inject life into the hosts and the latter made an instant impression, winning a free-kick down the right.

Kieran Trippier sent in a fine delivery and the on-rushing Saul converted with a thumping header from six yards for his fourth goal of season, keeper Fernando Pacheco getting a hand to it but unable to make the save.

Alaves almost levelled when a powerful aerial effort from Oliver Burke flew inches wide, but Atleti soon threatened at the other end when Llorente's long-range effort forced Pacheco to parry.

Llorente then showed superb pace and skill down the right before drawing a foul from Ruben Duarte, with Costa sending Pacheco the wrong way from the spot 17 minutes from time.

Three minutes into added time, Joselu sent a fine penalty into the top corner after Koke was penalised for handball, but it was too late for the visitors to recover.

Atletico took the chance to extend its advantage over Sevilla, which could only draw with Real Valladolid on Saturday (AEST), and now looks almost certain to claim a UEFA Champions League spot.

Atletico needed points in this match as its next one is a huge test away to Barcelona on Wednesday (AEST). Alaves, meanwhile, is at home to Granada a day later as it bids to halt a run of three straight defeats.