Celtic manager Ronny Deila has warned his players that they will have to be at their best on Thursday if they want to beat Astra Giurgiu in the Europa League.

The Scottish champions can reach the last 32 of the competition tomorrow night with a victory in Romania.

However, having seen his team earn a narrow victory in the reverse fixture two weeks ago, Deila is refusing to take the hosts lightly.

"European matches are the toughest matches we play as they are the best teams we have met so far this season," he is quoted as saying by the club's official website.

"They are a very strong team and we need to play at our best to get the three points, and if we do that we will have a very good chance of going through which is one our goals this season.

"They have a lot of individual quality and players who can score goals. They also try to play football and are used to dominating games, so we will have to defend very well and take our chances when we get them."

Celtic travel to Romania having won their last five matches in all competitions.