Chelsea manager Rafael Benitez believes that Basel proved their quality in progressing past Tottenham Hotspur in the Europa League on Thursday night.
Basel saw off Chelsea's Premier League rivals on penalties to make the semi-finals, and Benitez has admitted that they are a "dangerous" team to face in the last four after the two teams were drawn to play each other.
The 52-year-old told reporters: "Basel is not too far away so maybe playing them is a good option, but just because of that.
"They are a good team and they did well against Tottenham, so you can see that they are an offensive team.
"They play with a lot intensity so it will be a tough game. They are dangerous, for sure."
The first leg of the semi-final will take place in Switzerland on April 25, before the return match is played at Stamford Bridge on May 2.