Many bookmakers have rated Barcelona as 1/5 favourites to knock Chelsea out of the Champions League and advance through to May's final with relative ease.
Barca have history in their favour, having won three out of their last four meetings with the Blues.
However, they may have to take to the field at Stamford Bridge without the services of midfielder Xavi, who is reportedly struggling with a muscular complaint.
Centre-back Gerard Pique is also thought to be rated as 50/50 with a thigh problem.
Chelsea also have injury concerns of their own, mainly over defender David Luiz. Should the Brazilian fail to recover from a leg injury, then Gary Cahill is expected to play alongside captain John Terry.
The English defensive duo will face Lionel Messi, who has 61 goals in all competitions this season.
Perhaps equally as worrying for the home side is the fact that they have lost their last three semi-finals against Spanish opposition in UEFA competitions.
Current form:
Chelsea: LDWWDW
Barcelona: DWWWWW
Possible lineups:
Chelsea: Cech; Ivanovic, Terry, Cahill, Cole; Essien, Ramires, Lampard; Mata, Drogba, Kalou
Barcelona: Valdes; Alves, Puyol, Mascherano, Adriano; Busquets, Iniesta, Fabregas; Sanchez, Pedro, Messi
Sports Mole says: 1-2
