Arsenal defender Ben White will miss the rest of the season with a medial ligament injury, and it is understood he is unlikely to be fit for the World Cup with England.
The 28-year-old, who came off injured in the first half of Sunday's win at West Ham, will not require surgery on his injured knee, but no timescale for his recovery has been given.
White will miss the Premier League season run-in, with Arsenal facing Burnley and Crystal Palace in their attempts to win their first top-flight title in 22 years, and the Champions League final against Paris Saint-Germain on May 30.
The injury means White, who was brought back into the England fold by Thomas Tuchel in March, is a major doubt for this summer's World Cup in the USA, Canada and Mexico.
Tuchel selects his tournament squad on Friday May 22.
An Arsenal statement read: "Our medical team are now managing Ben's recovery and rehabilitation programme, with everyone fully focused on supporting the aim of Ben being ready for the start of our pre-season preparations."
Your Site' Sam Blitz:
Arsenal now have a right-back shortage in the most crucial part of their season.
Mikel Arteta is hoping to get the club's first Premier League title in 22 years plus their first ever Champions League trophy. But now there needs to be a rethink in the right hand side of the defence.
Not only is there this blow for White, but Arteta was not exactly confident in seeing Jurrien Timber again this season when asked about the Dutchman's fitness on Friday. Timber has not played since the 2-0 win over Everton on March 14.
So what do the Gunners do now? Cristhian Mosquera is the most likely candidate to take up the right-back mantle between now and the end of the season.
The Spaniard has played 430 minutes in that position this season in the Premier League and Champions League - and turned out in that role for the second half of the win over West Ham.
Mosquera has plenty of experience for Arsenal this season - and started the defeat to Manchester City in April at right-back - so can take up the mantle.
But a player who has made just 17 starts for Arsenal is now in line to play three of the biggest games in their history.
There is also Declan Rice as a right-back option, if needed. However, the England midfielder is a key cog in the middle of the park - and Arteta's experiment in putting Rice at right-back for 20 minutes at West Ham on Sunday did not work.
May 18: Burnley (H), Premier League, live on Your Site, kick-off 8pm
May 24: Crystal Palace (A), Premier League, live on Your Site, kick-off 4pm
May 30: Paris Saint-Germain (N), Champions League final, kick-off 5pm
June 1: England likely to fly to Miami
June 6: Friendly vs New Zealand in Tampa Bay
June 10: Friendly vs Costa Rice in Orlando
June 12/13: England to fly to Kansas City World Cup base
June 17: England vs Croatia - World Cup opener, Dallas
June 23: England vs Ghana - World Cup group stage
June 27: England vs Panama - World Cup group stage
