Tom Bradshaw stabbed home his fourth goal in as many games as a depleted Millwall earned an unlikely 1-0 win at Coventry.
The EFL had denied the Lions’ request for the match to be postponed and arrived in Coventry with just 15 senior players available.
Boss Gary Rowett filled his bench with Under-23 players Nana Boateng and Besart Topalloj and 15-year-old striker Zak Lovelace.
Millwall had to request for the teenager’s parents and school to approve his inclusion in the matchday squad as Rowett made four changes from his side’s 2-1 defeat to Peterborough on December 11, of which just one was Covid-related.
George Evans missed the match after a positive test, while Jed Wallace missed out through injury as Scott Malone and Benik Afobe dropped to the bench.
The Sky Blues were also without key men Simon Moore and Gustavo Hamer following positive tests, with Jamie Allen and Fankaty Dabo replaced by Tyler Walker and Todd Kane from the 1-1 stalemate at Huddersfield 18 days ago.
Despite a quiet opening 20 minutes in which Millwall enjoyed almost 60 per cent possession, Coventry midfielder Callum O’Hare looked the likeliest player to create an opening and found Walker, but the striker was unable to adjust his feet and get a shot away.
It was the former Aston Villa midfielder who had Coventry’s best chance of the match after 21 minutes, the ball sitting up kindly for him inside the penalty area but his half-volley was straight at Lions goalkeeper Bartosz Biaŀkowski.
From the resulting corner, Michael Rose’s header was cleared off the line before Dom Hyam’s acrobatic effort narrowly cleared the crossbar.
Walker was next to go close for the hosts as his improvised header from O’Hare’s cross also cleared Biaŀkowski’s goal.
Coventry had claims for a penalty waved away by referee Geoff Eltringham in the 70th minute before Bradshaw was in the right place with 11 minutes to go to poke home the winner inside the six-yard box after Jake Cooper flicked on Alex Pearce’s free-kick.
It was just Millwall’s second shot on target of the evening after they had thwarted a Coventry side that had lost just twice in nine outings.
Referee Eltringham waved away another penalty claim with 10 minutes remaining before Ian Maatsen fired over to condemn the Sky Blues to their third home defeat of the season.