"It's not an impossible mission, we'll keep going," Phelan told reporters on Thursday.
"We are up for the challenge ahead and players have bought into the new formation. We need to use it to its best."
The same formation has proved spectacularly successful for leaders Chelsea, who have gone on a 12-game winning streak since switching to it.
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Striker Abel Hernandez will definitely miss Friday's game. Phelan said the 26-year-old, who injured his groin at the start of November, is now jogging but still "10 days to two weeks" from full fitness.
(Reporting by Shravanth Vijayakumar in Bengaluru, editing by Neil Robinson)
