The Spaniard has cited the Swiss side's previous scalps in Europa League - the likes of Zenit and Tottenham - as evidence the semi-final second leg could be troublesome
Chelsea star Juan Mata has warned his team-mates that Basel still hold a threat in their Europa League semi-final tie despite the Blues' 2-1 lead from the first leg.
Rafael Benitez's side take a distinct advantage into Thursday's second leg thanks to goals from Victor Moses and a David Luiz's stoppage-time free kick.
But Mata cites Basel's previous scalps in the competition - the likes of Zenit St. Petersburg and Tottenham - as evidence the match has the potential to be troublesome.
Basel are 12/1 with Coral to be drawing at half-time but winning at full-time v Chelsea
"If we don't go into the game thinking about winning, thinking about defending well, thinking about trying to win again, it's going to be difficult.
"We still know we have to fight if we're going to be in the final. We got a great result in Switzerland, but now we have to play another 90 minutes and I'm sure they're not going to give up. They're a team who try until the end. It will be tough, for sure."
Chelsea are still fighting to secure Champions League football for next season by finishing in the Premier League's top four, but Mata has urged focus on winning a first-ever Europa League trophy.
He continued: "Our aims have to be winning this trophy and obviously being in the Champions League next season. Chelsea is a club which deserves to be in the Champions League every season.
"We can do it. If we play like we've been playing, all together, I think we can do both. Every time I watch a game on the TV from the Champions League I think it's a shame.
"But, on the other hand, I'd rather be positive and think we have the chance to win another trophy, as we did last season. Now we have another chance. For the team and for the club it's very important to have the chance to be in another European final.
"After winning the Champions League last season we have the chance to be in another final, trying to win another trophy, which will be new for the club. It means a lot for the club, for the supporters, for the players."