Chelsea had an approach for Neymar turned down in January. REUTERS

Chelsea have joined Real Madrid and Barcelona in the race to sign Santos striker Neymar, according to reports.

Roberto di Matteo, Chelsea's assistant first team coach, travelled to Stuttgart to watch the highly-rated 19-year-old play for his country against Germany on Wednesday.

Neymar scored his side's second goal as the hosts ran out 3-2 winner, the first time Germany have beaten Brazil for 18 years.

Chelsea have monitored the Santos striker since last summer and had a bid turned down in January after they failed to meet the £40m release clause in his contract.

Manchester City, Real Madrid and Barcelona have also been linked with the forward but Santos president insists the player will remain in Brazil until next year.

"Neymar will not leave until January 2012," he told Onda Cera.

"But it's not just Mourinho's club [Real Madrid] that is interested. There is also Barcelona, Juventus, Chelsea and Paris-Saint Germain. This is normal because he is a great player. Anyway, I will negotiate for him only in 2012."

Manager Andre Villas-Boas has also been linked with a move for Porto's central defender Rolando, as the Portuguese looks to bolster his defence ahead of the new campaign.

Villas-Boas worked with Rolando, 25, at his previous club Porto and is valued at around €15m.

Meanwhile, Fernando Torres is a doubt for Chelsea's opening Premier League match against Stoke this weekend after the £50m striker suffered a concussion in Spain's 2-1 defeat by Italy in Bari on Wednesday.

Torres, 27, lasted just 14 minutes before he was replaced by Fernando Llorente after he was hurt in a collision and taken to hospital as a precaution.