Manchester United were last night facing a losing battle in their bid to keep assistant manager Carlos Queiroz out of the clutches of the Portuguese FA. It is understood that the United board have offered Queiroz a £500,000-a-year pay hike to stay at Old Trafford.

But last night Queiroz told the United board and his mentor Sir Alex Ferguson that he would like to leave to manage the Portugal national team in the run up to the 2010 World Cup.

Carlos Queiroz (right) has been a strong influence on Cristiano Ronaldo (centre) since becoming assistant manager to Sir Alex Ferguson

Queiroz has been offered £1.5m-a-year and has given the Portugal FA a verbal agreement. He is expected to settle the details of the deal in the coming days.

United manager Ferguson has still not given up hope of persuading his trusted assistant to stay but last night in Portugal there was increasing optimism that the 55-year-old would accept the role.

Meanwhile, United medical staff were in Lisbon yesterday assessing the extent of Cristiano Ronaldo's ankle injury.

Ronaldo - who still hopes to leave United to join Real Madrid this summer - has been carrying the injury for some time and United are now seeking further specialist advice before deciding what action to take.

The fact that United sent staff to Portugal to see Ronaldo serves to indicate further that they are determined to keep him this summer.

Meanwhile, reports in Russia claimed Chelsea have agreed personal terms with playmaker Andrei Arshavin, who is due to meet Zenit St Petersburg president Alexander Dyukov today to discuss his future.