A fresh attempt to allow Premier League teams to make five substitutions per match this season has failed, the PA news agency understands.
A number of top-flight managers, including Liverpool's Jurgen Klopp and Pep Guardiola of Manchester City, have said the increase – which has been widely adopted in other competitions – is essential to protect player welfare amid a fixture schedule made even more congested by the coronavirus pandemic.
But it is understood it failed to achieve the required 14-club majority in a vote at a Premier League shareholders' meeting on Thursday.
There have been two previous votes on allowing five substitutes this season which have also failed to gain a sufficient majority, after clubs did agree to make the change for the conclusion of the 2019-20 season last summer.
The clubs have agreed to increase the number of substitutes allowed on the bench from seven to nine, which was the case for the end of the 2019-20 campaign as well.
The Premier League also announced it would apply to the game's law-making body, the International Football Association Board, to take part in a concussion substitute trial.
The protocol the Premier League has expressed an interest in allows each team to make up to two additional permanent substitutions in the event of a concussion, with the opposition allowed to make the same number of extra changes.
It could be introduced into the competition as early as next month, the league said. The league's medical working group will meet on Friday to further consider the protocols.
The Football Association plans to introduce the same concussion protocols into the men's and women's FA Cups, the Women's Super League and the Women's Championship.
The FA will also allow teams to make five 'normal' substitutes in those competitions.
The amendment of the law to allow clubs to introduce up to five substitutes in a match was proposed by FIFA and accepted by IFAB earlier this year, as a means to allow clubs to cope with a compressed calendar due to the suspension and resumption of competition due to Covid.
FA chief executive Mark Bullingham said on Wednesday he hoped Premier League clubs would back the change and was "surprised" that they had not already done so.
Bullingham said: "The reason we want (five subs) in the (FA Cup) is the reason most other leagues around the world have applied it. That is, for player welfare.
"Yes I am surprised that the Premier League hasn't brought it in. I think when we started off at an IFAB level, we fully expected all of the leading leagues to sign it off for the reason of a very congested season with a lack of pre-season.
"Whether that decision changes or not, that's obviously up to the clubs."