The Premier League is resisting calls to suspend all matches this weekend despite a raft of Covid-related postponements in the last 48 hours.
Manchester United's match against Brighton on Saturday is the latest to have been called off due to the number of Covid-19 cases in the Red Devils camp, with Thursday's game between Leicester and Tottenham also postponed.
The number of postponed weekend matches across England's top four divisions reached double figures by 3pm on Thursday, with the EFL announcing stricter Covid protocols including increased testing.
United are understood to have had only nine players available because of Covid and other injuries for Tuesday's game against Brentford, which was called off late on Monday night, and just seven for the Saturday lunchtime match against Brighton at Old Trafford.
Brentford manager Thomas Frank called for all of the weekend's top-flight matches to be postponed, with the highly-transmissible Omicron variant wreaking havoc with the schedule, but the league is currently intending to play as many games as possible.
In confirming the postponement of a second Manchester United match, the league said in a statement: "It is with regret that this is the fourth Premier League fixture to have been postponed in the past week.
"While recognising a number of clubs are experiencing Covid-19 outbreaks, it is the league's intention to continue its current fixture schedule where safely possible. The health and wellbeing of all concerned remains our priority."
Training operations at United's Carrington training complex have been suspended for "a short period" to help reduce the risk of further transmission.
It is understood United boss Ralf Rangnick had just nine first-team players available for Tuesday's appointment with the Bees because of Covid isolation and injury.
That figure had reduced to seven ahead of the scheduled weekend clash with the Seagulls.