Kieran Tierney is set for a scan over the next 48 hours as Arsenal reportedly fear the left-back has suffered a "serious" knee injury.
The Scotland international limped out of the 3-0 weekend defeat to Liverpool following a clash with James Milner.
The Daily Mail report the Gunners are concerned Tierney will now be ruled out for several weeks.
Scotland boss Steve Clarke will also await the scan results eagerly with the former Celtic defender one of the national team's most crucial players ahead of Euro 2020.
He delivered standout displays in each of the three recent World Cup qualifiers and registered a hat-trick of assists in the 4-0 win over the Faroe Islands last week.
A timescale of weeks rather than months would mean Tierney should be able to return for the Euros - which begins in June - but that clearly depends on the outcome of the scan.
“Kieran felt something in his knee," said boss Mikel Arteta on Saturday.
“He was in pain so it looks like he will be injured but we don't know how long for.”
