Manchester City midfielder David Silva believes it is "normal" that two-time defending champions Spain have been made the bookies' favourites after a scintillating start to their Euro 2016 campaign.

Vicente del Bosque's men have already secured their place in the last 16 after sweeping aside Turkey 3-0 on Friday after opening with a 1-0 win over the Czech Republic.

"At this stage it is normal that they make you favourites. We have won the last two European Championships and also for the games in the past few days," said Silva, who became the 10th Spanish player in history to reach 100 caps against the Czechs.

"But we need to keep our feet on the ground. We are calm and we need to continue that way."

Spain can guarantee top spot in Group D and in theory a place on the easier side of the draw for the knockout stage with just a point against Croatia in Bordeaux on Tuesday.

And Silva stressed the importance of winning the group to avoid a clash with old foes Italy in the last 16.

"We have had a very good start. We have won two games and now we have a very difficult game against Croatia.

"We need to win or draw to stay top of the group. We need to maintain our level and if it remains so high, we can win the tournament."

The Croatians have been rocked by crowd trouble that briefly halted their 2-2 draw with the Czech Republic on Friday.

UEFA have brought charges after at least 10 flares were lobbed from the Croatian corner of the Saint-Etienne stadium during the match.

The incident sparked outrage in the Balkan nation with Croatia coach Ante Cacic branding the perpetrators "sports terrorists" and President Kolinda Grabar-Kitarovic describing them as "enemies of Croatia".

However, hardcore supporters of Croatian club Hajduk Split, suspected of throwing the flares, have threatened on Facebook to also disrupt the next game against Spain.

On the field, Cacic's men could also be missing their most important player as Real Madrid midfielder Luka Modric hobbled off with a muscle injury with his side leading 2-0 against the Czechs, before the side collapsed, in part caused by the flare chaos.

Modric missed training on Sunday, but Silva said Spain had to be aware of Croatia's array of midfield talent also containing Barcelona's Ivan Rakitic and Mateo Kovacic of Real Madrid, regardless of whether Modric is fit or not.

"He is a fantastic player. He is playing very well, but if someone else plays they will also do well. We need to be prepared whether Modric plays or not."