Lucas Leiva is to undergo a scan on a thigh injury on Monday amid concerns at Liverpool that the influential midfielder could be sidelined for at least one month.

The Brazilian was replaced by Joe Allen in the 16th minute of Saturday’s Merseyside derby at Everton after suffering another thigh problem.

Lucas had missed the FA Cup replay win at Bolton Wanderers last Wednesday with a similar injury and was risked at Goodison Park despite not being 100% fit and being unable to train. He could now miss a demanding period of Liverpool’s season should scans confirm the club’s fears on the extent of the injury.

Saturday’s strain is in a similar area to the injury that forced Lucas to miss the FA Cup tie but believed to be a fresh problem. He would miss Premier League games against Tottenham Hotspur, Southampton and Manchester City if ruled out for four weeks plus the Europa League meeting with Besiktas.

Lucas has played a crucial role in Liverpool’s impressive improvement since November and in the 3-4-2-1 system employed by manager Brendan Rodgers.

Liverpool last lost a league game that the midfielder started on 20 September, away at West Ham United.