The centre-backs, therefore, looked certain to miss the Wembley showpiece with hamstring injuries.
On Tuesday, manager Roberto Di Matteo said he was hopeful both would be fit for the Champions League final on May 19.
Cahill was injured early in Chelsea's recent Champions League semi-final second leg against Barcelona.
Luiz has not played since limping out of the Blues' FA Cup semi-final against Tottenham at Wembley on April 15.
Meanwhile, John Terry urged his Chelsea team-mates to help Di Matteo land the manager's job full-time by winning Saturday's FA Cup final.
Blues captain Terry issued a ringing endorsement of caretaker boss Di Matteo ahead of the Wembley showpiece against Liverpool.
Clinching the FA Cup would boost Di Matteo's hopes of convincing Chelsea owner Roman Abramovich to hand him the reins permanently, something that would have the full backing of former team-mate Terry.
"It would do him no harm at all," Terry said. "He's obviously done very well in the league and all competitions to get us where we are today.
"To win it (the cup) will put himself in a very good position. He's not thinking of that at the moment, he's not letting the players get distracted by anything.
"He's very passionate, he's Chelsea through and through, and that's certainly rubbed off on the players. So, if we can do it with the added bonus that Robbie can get the job at the end, that'd be great."