Cardiff could pull themselves out of the relegation places if other results go their way, but they must beat West Ham in the Premier League on Saturday.
The Bluebirds are currently two points adrift of Southampton in 17th - who host third-place Tottenham on Saturday - but a win against West Ham could see them leapfrog the Saints.
But manager Neil Warnock said: "I don't think it's a must-win game but it's a very important game in the calendar. There are other games between now and the end of the season that will become must-win games, especially against the teams around us.
"We have to try and get something out of this game and be more positive than we have been. The lads have been a bit flat this week because it has probably been our worst week in the Premier League.
"You can see the disappointment of not being up to their own standards. We have to get back to that against West Ham. We have been a bit down because of the goals we have conceded. We want to make sure against West Ham we are on it from the start."
West Ham manager Manuel Pellegrini believes that playing a struggling Cardiff side will make their task harder, but they must go all out to win.
"It is my duty to convince the players that the position in the table of Cardiff will mean it is a more difficult game, not an easy one," he said.
"They will play at home, fighting against relegation and are not many points behind the teams above them, so we need to play with a high pace from the beginning, be a sharp team, be an aggressive team and try to attack and win the game."
Cardiff must reorganise their defence after Sol Bamba's season-ending injury. Bamba damaged knee ligaments in the 2-0 defeat at Wolves last weekend and Bruno Ecuele Manga is likely to be restored in his favoured centre-back position, with Lee Peltier remaining at right-back.
Harry Arter hopes to reclaim a midfield spot and Josh Murphy could return to the matchday squad after being dropped at Molineux.
Aaron Cresswell and Fabian Balbuena have been passed fit for West Ham. Cresswell limped off against Newcastle last week but has resumed training, while Balbuena is available for the first time since December after a knee injury.
Jack Wilshere, Andriy Yarmolenko, Winston Reid and Carlos Sanchez are long-term absentees.
- Cardiff have lost all three of their Premier League meetings with West Ham by a two-goal margin, losing the reverse fixture 3-1 in December.
- West Ham have won their last seven meetings with Cardiff in all competitions, scoring at least twice each time and conceding just three goals. They last had a longer winning run against an opponent between 1989-2000 vs Watford (9 games).
- Cardiff have lost their last three Premier League games by an aggregate score of 10-1, with two home defeats included in that run (5-1 vs Watford, 3-0 vs Everton).
- West Ham have only won one of their last eight Premier League away games against sides starting the day in the relegation zone (D4 L3), beating Fulham 2-0 in December.
- West Ham have won two of their last three Premier League games (L1), having won just one of their previous seven beforehand (D3 L3).
- Away from home, West Ham have lost four of their last five in the Premier League (D1), failing to score in each defeat.
- Cardiff have scored just seven first-half goals in Premier League games this season, a league-low. They've scored a league-high ratio 72 per cent of their goals after half-time in the competition this season (18/25).
- West Ham boss Manuel Pellegrini's first ever Premier League defeat was away at Cardiff in August 2013 with Manchester City - he's won his last two against the Bluebirds since that defeat.
Referee: Graham Scott
Assistants: Neil Davies, Derek Eaton
Fourth official: Andy Madley