Preview: King's Cup affects Spain's matchday 21

The semi-finals of the King's Cup knockout competition could have a major role to play in matchday 21 of the Spanish Liga Santander this coming weekend.

The midweek games played between Atletico Madrid and FC Barcelona and Celta Vigo and Deportivo Alaves mean the four sides have played two games a week every week since the Christmas break, giving their coaches a major selection headache and testing their squads to the limit.

Although Barcelona and Atletico have got bigger squads than Alaves and Celta, last weekend showed cup commitments have taken the edge off their league form and with Wednesday's first leg semi-final tie between the two in the balance after Barca's 2-1 win in Madrid, both Luis Enrique and Diego Simeone may have to rest key players this coming weekend.

Barca are first in action on Saturday and entertain Athletic Club in the Camp Nou. An injury hit Athletic recently lost 3-1 in the same ground in a previous round in the Cup, but their 2-1 home win against Barca means they have to be taken seriously, especially if Barca's changes cause them to struggle as they did away to Betis last weekend.

The Basques have not won in the Camp Nou for 19 years, but with their players fully rested, this could be Athletic's best chance of causing an upset in a long time.

Atletico Madrid are at home to Leganes for what should be a straightforward game against their near neighbors, but with tired legs, Atletico will have to be careful of a side which has signed well in the transfer window, adding some much-needed firepower in the form of Alberto Bueno and Nabil El Zhar.

In other circumstances Real Madrid's trip to play Celta Vigo would be a major banana skin on the road to the title, but after being knocked out of the Cup by Celta just over a week ago, Zinedine Zidane has had a week to prepare, while Celta's Cup game on Thursday has left them short of recovery time.

Also the chance of a historic cup final appearance means Celta are focusing on that competition rather than the league and that could make the task of a Madrid side which welcomes back Pepe and James Rodriguez, easier than it otherwise could have been.

Sevilla slipped up in the title race last weekend and face a difficult game at home to Villarreal as they look to get back on track without the suspended Nico Pareja, while fifth placed Real Sociedad are at home to struggling Osasuna in a Basque derby.

The weekend kicks off with a match between improving sides Deportivo la Coruna and Betis, with the home side needing a win to put space between themselves and the danger zone.

Likewise Valencia, who have several players out suspended, will need to show full commitment if they are to bounce back from last week's defeat in Las Palmas, at home to an ever-difficult Eibar.

Malaga are still looking for their first win under the guidance of 'Gato' Silva, while Sporting Gijon fans will be hoping Alaves are still suffering from their Cup exploits when the side from Vitoria visits El Molinon, where Sporting need a win to give themselves a chance of avoiding the drop. Enditem