BEN Thompson could miss Millwall's League One clash with Southend on Saturday after going off at half-time in the 2-0 win at Coventry last weekend with a tight hamstring.
Thompson was having a scan this week to determine if there was any damage, but Lions boss Neil Harris was hopeful it was only a minor setback.
Thompson, who signed a new deal with the club until 2020 last week, has been a first choice in midfield since a suspension for Shaun Williams and an injury to Ed Upson gave him his chance a year ago.
He has played in 35 of Millwall's 39 games this season, but his potential absence could open the door for Jimmy Abdou (above) or Calum Butcher to replace him.
Abdou, who was Thompson's midfield partner in the latter part of last season, came on at the break at the Ricoh Arena, but hasn't started a league game since the 3-2 win at Bury on November 26.
Butcher, meanwhile, has struggled since his move from Burton Albion in the summer. He has started just four games in all competitions for Millwall and an ankle injured has prevented his involvement recently.
He was fit for the game against the Sky Blues, but didn't make Harris' match-day squad.
If Thompson is out both players will be in contention to start against the Shrimpers.
Harris said: "Jimmy did very well when he came on on Saturday. He gave us a lot with his energy and his work rate. His positional play was also outstanding and he kept the ball really well, so I was pleased with him.
"Jimmy has had to be patient and bide his time so it's good for him that he got some minutes.
"Calum was unfortunate at the weekend, he was fit and travelled with us. He's a top lad and a top pro and a really good player.
"The competition in midfield is rife at the moment and Butch has missed out after coming back from his ankle injury.
"But he certainly comes into the reckoning for the squad for this weekend, depending on Thommo's injury.
"Butch has come into an area with a lot of competition but he gives us something different, he gives us a goal threat going forward in the middle of the park.
"He's had to be patient, the form of the two boys in central midfield has been outstanding. Jimmy and Butch are both aware that we've had a settled and winning side but they've both put their heads down and worked hard.
"If Thommo is a risk for Saturday then both of them will be looking for the opportunity to play."
Defender Shaun Hutchinson is a doubt with a calf problem, but Millwall have kept three clean sheets in four games since Jake Cooper made his debut after joining on loan from Reading.
Southend, meanwhile, have been in scintillating form in the last three months and last weekend came from behind to beat Scunthorpe 3-1, the Iron's first league loss in 2017 and a result that dropped them to second in the table.
Phil Brown's side have lost just one of their last seventeen League One games to move from the relegation zone after a 3-0 loss at Rochdale in October to the play-off places.
Brown boosted his squad depth by adding striker Theo Robinson from Lincoln City on transfer deadline day.
Millwall record against Southend:
Won 38 Drawn 22 Lost 27
Probable Millwall team:
Millwall: 4-4-2: Archer; Romeo, Webster, Cooper, Craig; Wallace, Abdou, Williams, O'Brien; Gregory, Morison.
Millwall 4/5 Draw 17/5 Southend 7/2
Image: Millwall FC