Sheffield United midfielder John Fleck was taken off on a stretcher in the second half of his side's 1-0 win at Reading.
With the Blades leading through Jayden Bogle's 56th-minute strike, Fleck went down apparently unchallenged - and his team-mates quickly indicated for the medics to run onto the pitch and tend to him.
Fleck, 30, appeared to receive emergency attention before, after a 10-minute delay, he was taken off on a stretcher and out of the ground to a waiting ambulance.
United said on Twitter that Fleck was conscious when he left the stadium via the ambulance gate.
West Brom ended a run of four successive away defeats but gave up more ground in the automatic promotion race as they were held to a goalless draw at Blackpool.
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Baggies keeper Sam Johnstone made a brilliant double stop to deny Gary Madine and Keshi Anderson while Matt Clarke came close to snatching a late winner for the visitors.
Chris Wilder is still waiting for his first win as Middlesbrough boss after Preston hit back from behind to claim a 2-1 win at the Riverside Stadium.
Paddy McNair's 33rd-minute header looked set to get Wilder's regime up and running after he marked his debut in the dugout with Saturday's 1-1 draw against Millwall.
But Ched Evans headed Preston's equaliser in the 77th minute and four minutes later, Emil Riis Jakobsen lashed an unlikely winner for Frankie McAvoy's men.
Birmingham ended a run of two straight defeats by clinging on for a goalless draw at former tenants Coventry despite having Ryan Woods sent off eight minutes from time.
Nottingham Forest also ended the night with 10 men after Jack Colback was sent off for two bookable offences in their goalless draw with Luton at the City Ground.
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Plymouth crashed to their second straight defeat while Rotherham took over at the top of League One with a 2-0 win at Ipswich.
Two late goals from Anis Mehmeti gave Wycombe a 3-0 win over Ryan Lowe's men at Home Park after Sam Vokes had opened the scoring on the hour mark.
The result saw Wycombe leapfrog Argyle into second while Rotherham are top on goal difference after goals from Ben Wiles and Shane Ferguson saw them cruise home at Portman Road.
Wigan hit back from two goals down to salvage a point at Cambridge, who led through goals from Joe Ironside and Adam May either side of the interval.
Will Keane levelled after 84 minutes and Callum Lang equalised three minutes later to extend the Latics' unbeaten run to three games.
Sheffield Wednesday also left it late as they came from behind to beat MK Dons 2-1 at Hillsborough.
Scott Twine lashed a 47th-minute opener for the visitors but their hopes of making it four straight wins were dashed when Lee Gregory equalised after 83 and Josh Windass netted the Owls' winner in injury time.
Johnnie Jackson's unbeaten start in charge of Charlton continued but the Addicks blew a two-goal lead to draw 2-2 at Morecambe.
Goals from Diallang Jaiyesimi and Conor Washington put the visitors in control inside the opening half-hour but Cole Stockton's penalty reduced the deficit and Anthony O'Connor headed a 72nd-minute leveller.
Ten-man Shrewsbury salvaged a point at home to Sunderland as the Black Cats' campaign continued to stutter.
Alex Pritchard had given the visitors a 16th-minute lead before the Shrews had David Davis sent off on the stroke of half-time - but they still grabbed a point through Danny Udoh's 64th-minute effort.
Portsmouth stretched their unbeaten run to six games as goals from Marcus Harness, George Hirst and Recco Hackett-Fairchild saw them cruise to a 3-0 win at Lincoln.
Oxford shrugged off their recent coronavirus issues to beat Fleetwood 3-1 at Kassam Stadium.
The Us, who had been forced to postpone their weekend clash with Wigan, led through Luke McNally and Cameron Brannagan, then wrapped up the points through Nathan Holland after Jay Matete had reduced the deficit.
Burton brought an emphatic end to four straight defeats as they thrashed Accrington 4-0.
Daniel Jebbison and Jon Smith each helped themselves to a double as Stanley saw their winless run stretch to five games.
Wimbledon came from behind to beat bottom club Crewe 3-2.
Chris Long put Alex in front after 11 minutes but Jack Rudoni's header and a double from Ollie Palmer sealed the points for the Dons before Chris Porter's last-gasp consolation.
Goals from Sean Long and Alfie May helped Cheltenham to a 2-0 win at injury-hit Gillingham.
Bolton beat Doncaster 3-0 with goals from Eoin Doyle, Elias Kachunga and George Thomason, while the visitors had Joseph Oluwu sent off just before half-time.
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Exeter's record-breaking run of 20 games without defeat finally came to an end as they sank to a 3-1 defeat at Colchester.
First-half goals from Sylvester Jasper and Noah Chilvers paved the way for the Grecians' first loss since their 3-0 reverse to Leyton Orient in August.
Padraig Amond gave Exeter hope when he reduced the deficit in the 69th minute, but a Freddie Sears effort five minutes later sealed Colchester's win.
Exeter's defeat enabled Forest Green to stretch their lead to five points as a second-half double from Matt Stevens gave them a 2-0 home win over Barrow.
Port Vale's dip in form continued as they followed up Saturday's shock loss to Oldham with a 1-0 home defeat to Walsall.
Brendan Kiernan struck the winner for the Saddlers on the half-hour mark, while Vale had Tom Conlon sent off in the 72nd minute.
Swindon jumped up to third as they beat Hartlepool 3-1 to record their third straight win.
Jonathan Williams opened the scoring with a 52nd-minute header and, despite Matty Daly's leveller for the visitors, Tyreece Simpson and Jack Payne struck late to seal the win.
Nine-man Salford claimed an improbable point at home to Bristol Rovers, who led through Sam Nicholson's 14th-minute opener.
Salford had Matthew Willock sent off just before half-time then Ashley Hunter also dismissed in the 89th minute, but there was still time for Brandon Thomas-Asante to equalise in injury time.
Oldham failed to follow up their win over Vale as they went down 2-1 at Northampton. Jon Guthrie and Kion Etete put the Cobblers in command before Carl Piergianni reduced the deficit.
Dominic Telford's 12th goal of the season salvaged a late point for Newport at Crawley, who had led through Kwesi Appiah.
Struggling Carlisle saw their winless league run stretch to 11 games as goals from George Thomson and Alex Pattison earned Harrogate a 2-0 win at Brunton Park.
Jake Scrimshaw's 64th-minute equaliser earned rock-bottom Scunthorpe a precious point in a 1-1 draw against Orient, who led through Aaron Drinan's eighth of the season.
Goals from Louis John and Omar Bugiel gave Sutton a 2-0 win over Mansfield, while managerless Stevenage earned a 2-2 draw at Rochdale, with Elliott List scoring twice to cancel out efforts from Jake Beasley and Josh Andrews for the hosts.
Tranmere came from behind to beat Bradford at Prenton Park. Levi Sutton gave the Bantams the lead, but Kieron Morris levelled and Paul Glatzel struck a second-half winner.