The defending Premier League champions suffered a disappointing 4-1 loss to London rivals Watford last week.
Chelsea FC have now lost their last two Premier League outings following Bournemouth’s 3-0 win at Stamford Bridge in January.
The Blues started the weekend in fourth place in the Premier League table and a mere points ahead of Tottenham Hotspur.
Antonio Conte’s men will host 20th-placed West Brom at Stamford Bridge on Monday night looking to end a two-game losing run.
Chelsea FC face a big month with a FA Cup fifth-round clash against Hull City before games against Manchester City and Manchester United.
The Blues will also take on La Liga leaders Barcelona in the first leg of their Champions League last-16 clash.
Rooney warned that Chelsea FC can’t be distracted by bigger games further down the line ahead of the visit of West Brom on Monday night.
“Their most important game is the West Brom,” Rooney told Sky Sports. “They have to win that game. They have to go and get three points.”
Chelsea FC won the Premier League title with two games to spare last season after the Blues finished seven points clear of Tottenham.
Chelsea FC signed Everton midfielder Ross Barkley, AS Roma defender Emerson Palmieri and Arsenal striker Olivier Giroud in the January transfer window.
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