Referees chief Mike Riley may be forced to fast-track a group of young officials into Premier League action as his team comes under increasing fixture pressure, Sky Sports News understands.
The sacking of Bobby Madley in August, plus Roger East failing the start-of-season fitness test, has put added pressure on the 16 remaining officials.
East, 53, is yet to officiate a Premier League game this campaign, but Sky Sports News understands he has passed the fitness test in the last fortnight. However, once again, he will not be officiating this weekend.
Another top referee Simon Hooper has been injured since the start of the season, and is also yet to officiate a Premier League match.
There is no age limit to refereeing in the Premier League. However, Riley's select group also includes Mike Dean, 50, Martin Atkinson and Andre Marriner, both 47, and 46-year-old Lee Mason - and there are growing concerns that as much as a third of the top tier of referees will soon have to be replaced.
The premature loss of Howard Webb and Mark Clattenburg also dealt severe blows to the Premier League's referee resources.
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However, Riley is understood to have dismissed calls for referees to be brought in from abroad and believes the current crop of young refs, many of whom are in the PGMO's Select Group 2, are the best young group for many years.
Ironically, Andrew Madley, older brother of Bobby Madley, is one of the most highly rated by the PGMOL. Others include Rob Jones, Peter Bankes and Darren Bond.
Neil Swarbrick and Mike Jones both retired from Premier League action at the end of last season, but are both involved in mentoring the PGMO's young crop of officials.
Two Select Group 2 referee will be used as VAR officials this weekend, as five Premier League matches undergo tests of the replay system.