Chelsea's problems continued on Tuesday night as they suffered a 2-0 defeat to Leicester City in the Premier League, which has left the Blues down in eighth position in the table, 11 points off the summit.
Frank Lampard's side have only won two of their last eight in the league and therefore the FA Cup could prove a welcome distraction, particularly as they breezed past Morecambe in the third round of the competition, with Timo Werner and Kai Havertz, who have both struggled this season, on the scoresheet.
Chelsea are actually bidding to progress to the fifth round of the FA Cup for the 23rd time in their last 26 attempts, while they have not lost to a side from a lower division since 2015, when Bradford City recorded a famous victory in the fourth round of the competition.
The capital giants have won the FA Cup on eight occasions, the last of which was in 2018, while they also reached last season's final, losing 2-1 to Arsenal at the start of August.
The Blues actually met Luton in the semi-finals of this competition in 1994, recording a 2-0 victory at Wembley courtesy of a brace from Gavin Peacock, before losing to Manchester United in the final.
Luton, meanwhile, are actually appearing in the fourth round of the FA Cup for the first time in eight years, having beaten Reading 1-0 in the third round of the competition at the start of January.
The Hatters have only reached the fifth round once since their semi-final loss to Chelsea in 1994, and there is no question that they will be the underdogs to overcome the Premier League outfit on Sunday afternoon.
Luton last overcame top-flight opposition in this competition in 2012-13 when they beat Norwich City, while they have won three of their last five matches during a strong run of form.
Nathan Jones's side will enter this match off the back of a 1-0 defeat at Brentford in the Championship on Wednesday night, but a strong season to date has seen them collect 33 points from their 25 matches to sit 13th in the table, 13 points clear of the relegation zone.
Chelsea FA Cup form: WWWWLW
Chelsea form (all competitions): LDLWWL
Luton Town FA Cup form: WWDLLW
Luton Town form (all competitions): LWWLWL
Lampard will make wholesale changes from the side that started against Leicester, with the starting XI expected to have a similar look to the one that featured against Morecambe in the last round.
Chelsea possible starting lineup:
Kepa; Azpilicueta, Zouma, Christensen, Emerson; Mount, Gilmour, Havertz; Hudson-Odoi, Werner, Ziyech
Luton Town possible starting lineup:
Sluga; Pearson, Bradley, Rea; Bree, Tunnicliffe, Moncur, Dewsbury-Hall, Potts; Hylton, Collins
We say: Chelsea 2-0 Luton Town
Luton will be eyeing a huge scalp on Sunday afternoon, but we are finding it difficult to look past Chelsea on this occasion. The Blues will be determined to bounce back from a disappointing defeat at Leicester and should have more than enough to overcome their Championship opponents at Stamford Bridge.