Gareth Bale & Cristiano Ronaldo
Real Madrid forward Gareth Bale, 26, has been sidelined for three weeks with a calf injuryReuters

Gareth Bale could miss Real Madrid's Champions League round of 16 trip to Roma after aggravating his muscle injury, according to reports. Bale, 26, has been out of action since injuring his calf in Real's 5-1 win over Sporting Gijon on 17 January.

Initial reports suggested that the Wales international would return to action in time for the home game against Athletic Bilbao on 13 February. However, Spanish daily AS says the forward is now certain to miss the Athletic clash and is a major doubt for the trip to Rome on 17 February, after he aggravated his injury by training on a special sand pitch at Real's training ground.

The news is a major blow for Madrid coach Zinedine Zidane, with the Champions League increasingly seen as the club's best shot at winning a major title this season. Real are four points behind La Liga leaders Barcelona, who have two games in hand, and were thrown out of the Copa del Rey in December for fielding an ineligible player.

Improved form

Bale has scored 13 goals in 15 league appearances for Madrid this season, including a hat-trick in Zinedine Zidane's first game as club boss against Deportivo La Coruna.

Marca reported in January that the Madrid hierarchy were pleased with Bale's improved attitude and application this season and were keen to reward the Wales forward with a new contract. The paper claimed that an improved contract would represent recognition of Bale's elevated standing in the dressing room, where he is seen as Cristiano Ronaldo's successor.

Gareth Bale
Bale has scored 52 goals in 109 appearances for Real MadridReuters

Bale joined Madrid on a six-year contract from Tottenham Hotspur for a world-record fee of €100.8m ($112.8m) in 2013 and has scored 41 goals in 73 league appearances. Meanwhile, left-back Marcelo will also miss the Roma match after dislocating his shoulder against Granada.

A statement on Real's website read: "After tests carried out today on the player Marcelo at the Sanitas La Moraleja University Hospital, he has been diagnosed with a acromioclavicular shoulder joint dislocation. His recovery will continue to be assessed."