Spain coach Vicente del Bosque has warned that his side can't be complacent in their quest to qualify for the European Championships in France next year.
Sevilla winger Vitolo and Villarreal goalkeeper Sergio Asenjo were called up to Del Bosque's squad for the first time on Friday for matches against Ukraine and the Netherlands.
Spain host Ukraine in Seville in a Euro 2016 qualifier on March 29 before hoping to avenge their 5-1 humiliation by the Dutch at last year's World Cup in Amsterdam four days later.
The European champions are only second in their qualification group, three points behind Slovakia and just ahead of Ukraine on goal difference.
And Del Bosque believes the strong showings of Ukranian sides Shakhtar Donetsk, Dynamo Kiev and Dnipro Dnipropetrovsk in European competitions this season should serve as a warning to his side.
"I was watching the games of the Ukranian teams and they are very good. I seems it is a routine things for me to praise the opposition, but it is the truth," he said.
Dynamo Kiev thrashed Everton 5-2 on Thursday to progress to the last eight of the Europa League where they will be joined by Dnipro, who eliminated Ajax on away goals.
"Yesterday I watched the Europa League games and they have very good forward players and the Shakhtar players at the back too.
"We need to be careful because we have a lot at stake. If we don't win it would be a worrying step backwards."
Athletic Bilbao's Mikel San Jose is another surprise inclusion, whilst Mario Suarez and Alvaro Morata are rewarded for their impressive Champions League displays with Atletico Madrid and Juventus this week respectively.
Barcelona's Sergio Busquets is also included despite suffering from a sprained ankle which is expected to keep him out of this weekend's El Clasico against Real Madrid.
"We had the all clear to call him up and see how he recovers this week," added Del Bosque.
"We will have time to take a decision on Tuesday or Wednesday after seeing if he is in condition to play or not."
Squad in full:
Goalkeepers: Iker Casillas (Real Madrid), David de Gea (Manchester United), Sergio Asenjo (Villarreal)
Defenders: Sergio Ramos, Dani Carvajal (Real Madrid), Gerard Pique, Jordi Alba, Marc Bartra (Barcelona), Juanfran (Atletico Madrid), Raul Albiol (Napoli), Juan Bernat (Bayern Munich)
Midfielders: Sergio Busquets, Andres Iniesta (Barcelona), Mario Suarez, Koke (Atletico Madrid), Mikel San Jose (Athletic Bilbao), David Silva (Manchester City), Santi Cazorla (Arsenal), Cesc Fabregas (Chelsea), Isco (Real Madrid)
Forwards: Diego Costa (Chelsea), Alvaro Morata (Juventus), Vitolo (Sevilla), Pedro Rodriguez (Barcelona)
Source: AFP
