Gareth Bale
Bale could make his Real Madrid debut with both Ronaldo and Isco unavailable. (Reuters)

Gareth Bale could have the opportunity to make his Real Madrid debut without the presence of Cristiano Ronaldo alongside him with the Portuguese star a doubt for Saturday's clash with Villarreal.

The former Manchester United star was in remarkable form on Friday night as he struck a hat trick against Northern Ireland in a World Cup qualifier despite not being 100 per cent fit to compete at Windsor Park.

The 28-year-old has now been ruled out of Portugal's friendly against Brazil on Tuesday evening with tendinitis, a knock that could see the forward side lined for Real's visit to the Estadio El Madrigal on Saturday evening.

"Ronaldo had a week of intense treatment, he made an enormous sacrifice and now he needs to rest," Portugal's team doctor Henrique Jones was quoted as saying on the official FIFA website.

Should Ronaldo not return in time for that trip, Bale could be given the opportunity to take centre stage on his debut for the club after his £86m move from Tottenham Hotspur last month.

The 24-year-old was named on the bench but did not feature in Wales' 2-1 defeat to Macedonia last Friday, and will not start Tuesday's clash with Serbia either, his national team manager Chris Coleman confirmed.

Although the Welshman has not played any club football since a pre-season friendly against Swindon Town in mid-July, concern over Ronaldo's fitness could very well see the Portuguese rested and Bale thrust to the focal point of Carlo Ancelotti's attack.

Those chances may have also been improved after Spain international Isco suffered an ankle injury last week.

The attacking midfielder, Real's top scorer so far this season, was left out of his country's win over Finland last Friday and was sent back to Madrid for treatment ahead of tonight's friendly with Chile, leaving Ancelotti with a problem ahead of the return of domestic matters this weekend.

Bale received his own fitness boost on Monday when a scan on a groin injury revealed no damage.

While Real Madrid are yet to comment on the status of Ronaldo, Spanish newspaper AS report he has already travelled back to the Spanish capital to receive treatment in efforts from the club to get their leading goal scorer last season fit in time for Saturday.

However, the report does suggest that the tendinitis from a thigh injury has plagued the player for a number of weeks, which could throw his participation in doubt.

Despite carrying a perceived knock, Ronaldo was in spectacular form against Northern Ireland as his three goals hauled him above Portugal legend Eusebio in the nation's all-time leading goal scorer ranks. The Real Madrid star is now just four goals off Pauleta's all-time record of 47.