The two-legged tie gets underway in Basel on Thursday night and the Swiss side have already beaten one team from London, knocking Spurs out on penalties after an epic quarter-final.
"Basel is in the semi-final and deserve to be there," said Benitez. "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.
"Philipp Degen was my player (at Liverpool) and is a good professional, a worker who enjoys playing football. They have some good young players and others with more experience."
Basle head coach Murat Yakin is confident his side can overcome the Blues.
The former Switzerland international took the helm when the team was struggling in October but has led a revival which he wants to cap with a place in the final on May 15.
"I'm not dreaming, I'm very realistic," he said. "We're talking about reaching the final here.
"When I started, we were in the very last spot in our group.
"From there I presented my vision that I had to the team and the vision that I had to maybe reach the final in Amsterdam.
"The team grew in this competition, showing great performances, at home especially. It sets up a good advantage for the second leg then.
"We need one great game and maybe one OK game to make it to the final."