With Carles Puyol suspended and Rafael Marquez injured, Barcelona look horribly exposed in central defence, especially with the powerful presence of Didier Drogba poised to overpower whoever is drafted in.
Amid the jubilation of Barcelona's 6-2 thrashing of Real Mad rid on Saturday, Chelsea's spies will have reported back that Real's two goals were via the heads of Gonzalo Higuain and Sergio Ramos courtesy of slack marking in the middle.
Gerard Pique, Eric Abidal and Martin Caceres, who has looked shaky this season, are vying for the two slots while manager Pep Guardiola could spring a surprise by dropping muscular midfielder Yaya back to counter the physical presence of Drogba.
The big Ivorian will be licking his lips at the prospect of attacking that soft centre, and when it comes to set pieces, he will have considerable reinforcement.
Centre backs Alex and John Terry, Michael Ballack, Mikel, and fullback Branislav Ivanovic, who headed two goals in the quarter-final against Liverpool, have considerable presence in and Frank Lampard has an unerring delivery.
Ballack and Terry will have loved every word of Barcelona's complaints and no doubt plan to deliver a similarly uncompromising welcome on Wednesday.
Hiddink, aware of his side's set-piece and aerial threat but also concerned by Barcelona's dangerous attack and ability to snatch an away goal, is likely to start with the same steady approach with Drogba ploughing a lone furrow up front.
Nicolas Anelka, who scored his 22nd of the season on Saturday, will be desperate to start but is more likely to return to the bench, from where can be introduced to add more variety to Chelsea's attack if plan A fails to come off.
"I like to have a flexible team," Hiddink said after seeing his two strikers operate successfully together again. "I don't want them surprised with two strikers playing together.
Chelsea are also stiffened at the back with the return from suspension of Ashley Cole.
The England left back is at his best when fully concentrated on man-marking a dangerous winger, and Lionel Messi, who admittedly did not much out of stand-in Jose Bosingwa in the first leg, will have to be at his elusive best to make his mark.
Probable teams:
Chelsea: 1-Petr Cech; 2-Branislav Ivanovic, 26-John Terry, 33-Alex, 3-Ashley Cole, 15-Michael Essien, 12-John Obi Mikel; 13-Michael Ballack, 8-Frank Lampard, 15-Florent Malouda; 11-Didier Drogba.
Barcelona: 1-Victor Valdes; 20-Daniel Alves, 3-Gerard Pique, 2-Martin Caceres, 22-Eric Abidal; 6-Xavi, 24-Yaya Toure, 8-Andres Iniesta; 10-Lionel Messi, 9-Samuel Eto'o, 14-Thierry Henry.
Referee: Tom Henning (Norway)
