Everton manager David Moyes confirmed in his pre-match press conference that the French striker is unlikely to feature against a club he has scored nine times against in 13 Premier League and FA Cup appearances thanks to a hamstring injury.
The Frenchman returned to training this week, raising hopes that he could make the match at Stamford Bridge, but Moyes put a dampner on those hopes saying 10-14 days was still the time frame for recovery.
Jack Rodwell will also miss out though Moyes was encouraged by his recovery from a groin injury sustained on England duty last week and thinks he will be able to return for the Sunderland game next Saturday.
If Saha does miss out then I really hope Jermaine Beckford is given a starting role. The former Leeds striker has made an impact from the bench in recent weeks, with his pace and enthusiasm a great asset to throw on late in a game. But after the dreadful performance at Bolton last week changes need to be made and Victor Anichebe - who was as bad as anyone at the Reebok - should make way.
When previewing the first game I labelled it a 'save-our-season' match and while that still applies - a cup run will sustain interest and excitement among the fans - a defeat at Stamford Bridge won't signal the end of our campaign.
We are very much in a relegation battle and need to pick up some wins in the next few weeks to try and drag ourselves away from trouble. Last Sunday we looked every inch a side who think they are too good to turn down but don't put in the performances that merit it.
And while I would love for us to go on a decent run in the cup (Reading at home next up would give us a great chance of doing that) it can't be at the expense of Premier League points.
It would though go some way towards convincing the current players and any prospective ones that we are still competitive outfit - even if it is papering over the cracks.
And from a personal point of view the cup brings hope and excitement - those early months in 2009 as we made our way to Wembley were great times to be an Evertonian. A relegation battle just doesn't provide that sense of excitement!
The 6,000 travelling army of Blues tells you everything about what we think of this game. We crave success and the chance to go to 'big' matches - defeat will end our chances for another season.
Boys, it's over to you.
• Chelsea have not beaten Everton since the 2009 FA Cup final, when they prevailed 2-1.
• This is the ninth time these clubs have been drawn to meet each other. Chelsea lead by six wins to two.
• The Merseyside club last prevailed against Chelsea in the fifth round in February 1956.
• Won four of the last seven in all competitions.
• Avoided defeat in six of the last seven in league and cup.
• Chasing their first goal in three games.
• Aiming to become the first club to win three successive FA Cups, since Blackburn in 1884, 1885 and 1886.
• Unbeaten in 15 FA Cup ties.
• Their only defeat in 26 ties since January 2007, was 1-0, away to Championship club Barnsley in the quarter-finals in March 2008.
• Scored eight goals in two FA Cup matches this season, and only conceded two in the last eight ties.
• Not been eliminated in the fourth round, or earlier than that, since third round victims to Manchester United in January 1998.
• Won one of the last six in all competitions, and lost two of three.
• Not won away from home in three outings (D1, L2)
• Thrashed Scunthorpe 5-1 at Glanford Park in the third round; Everton's last win on the road in any competition.
• Won the cup for the fifth time in 1995, and made one appearance in the final since then when Chelsea beat them 2-1 on 30 May 2009.
• Not dismissed a fellow Premier League club since Manchester United in the 2008/09 semi-finals, after a penalty shoot-out.
Referee: Phil Dowd (Staffordshire)
Assistant referees: John Flynn and Stuart Burt