Gareth Bale missed Wales training on Monday and remains doubtful for Thursday's high-profile friendly with Spain in Cardiff, live on Sky Sports.
Bale sat out Wales' training session after coming off in the final 10 minutes of Real Madrid's 1-0 La Liga defeat at Alaves on Saturday.
It is understood the 29-year-old forward has suffered a recurrence of a groin injury which saw him miss Real's Champions League loss to CSKA Moscow last week.
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Wales' medical team will continue to assess Bale in the next 48 hours ahead of the 19.45 kick-off on Thursday.
Bale is set to be presented with an award before the Spanish game to celebrate his Wales scoring record, having passed Ian Rush's 28-goal mark earlier this year.
Aaron Ramsey also missed training after playing in Arsenal's 5-1 win at Fulham on Sunday, while young Leeds striker Tyler Roberts sat out the session following a heavy recent workload.
After the Spain game, Wales face the Republic of Ireland at the Aviva Stadium in Dublin on October 16, having beaten Martin O'Neill's side 4-1 last month.