Chelsea interim manager Rafael Benitez has insisted that Basel will provide a threat for his side when they meet in the first leg of their Europa League semi-final.
The Swiss champions, who defeated Tottenham Hotspur in the last round, host the Blues at St Jakob-Park on Thursday.
"Basel is in the semi-final and deserve to be there," Benitez told reporters. "They've worked very hard, have played well, and are well organised. They press well and launch good counter-attacks.
"They have good players with pace and ability, so we will have to do really well if we want to win."
Chelsea booked their place in the semi-finals of the competition with a 5-4 aggregate victory over Rubin Kazan.