Watford has no major injury worries as they prepare to make the journey to Selhurst Park.
Influential defender, Clarke Carlisle has recovered from a hip injury collected during the Golden Boys recent odd goal in three victory at Queens Park Rangers, and is expected to be named in the squad, leaving just long term absentees, Hamuer Bouazza (foot) and Dominic Blizzard (viral) as definite non starters.
Crystal Palace meanwhile are almost certain to recall star striker, Andrew Johnson to their starting line-up in place of Dougie Freedman, after the England World Cup hopeful was rested during the South Londoners one goal reversal at Sheffield United last Sunday.
Experienced midfielder, Michael Hughes is also expected to return after being left out at Brammall Lane, and talented defender Danny Butterfield is also in the shake-up as Eagles manager, Iain Dowie looks to set Watford a tough task ahead of the second leg at Vicarage Road next Tuesday.