FC Basel 1-1 FC Porto

• Clattenburg books nine players
• Ref rules out Porto goal after delay
• Porto awarded late penalty
• Gonzalez scores for Basel, Danilo for Porto

Referee Mark Clattenburg ruled out a Porto goal before awarding a late penalty in a heated Champions League tie in Basel.

The English official disallowed a Casemiro goal after a long delay - but replays showed he was correct as two other Porto players were offside.

Derlis Gonzalez gave Basel a first-half lead, but Danilo equalised from the spot after Walter Samuel handled.

Paraguay international Gonzalez, a former Benfica youth-team player, held off Alex Sandro as he burst on to Fabian Frei's through ball in the 11th minute, and slotted a shot beneath keeper Fabiano.

Gonzalez, who took a blow to the head in the process of scoring, attempted to carry on for more than 10 minutes after receiving treatment, but looked groggy and had to be helped off.

Clattenburg faced criticism in Europe last season, when Juventus coach Antonio Conte said he was not good enough to referee their Europa League semi-final defeat against Benfica.

Conte accused the referee at the time of not doing enough to stop what he believed were spoiling tactics from the Portuguese side.

However, even though he had a tough job keeping control of a fractious match at St Jakob Park, he appeared to get the crucial decisions correct.

Paulo Sousa's Swiss champions had to defend solidly as their Portuguese opponents dominated for long periods.

It was a tough night for Porto's 25-goal top scorer Jackson Martinez, who had to contend with the imposing physical presence of Argentine veteran Samuel.

The 36-year-old defender, who has made just eight starts since arriving at Basel from Inter Milan last July, was perhaps fortunate not to concede a first-half penalty when he appeared to drag Martinez by the sleeve.

Porto struggled to find an equaliser, as Casemiro planted a header wide of the near post from a Cristian Tello corner in the first half, moments after Danilo's low left-foot shot from just outside the penalty area had been pushed aside by keeper Tomas Vaclik.

Clattenburg's decision to rule out Casemiro's goal three minutes into the second half prompted controversy.

The Brazilian midfielder was onside as he turned in the loose ball from close range after Vaclik had saved a Maicon header from Tello's corner.

But Clattenburg - after a delay in which he consulted an assistant - ruled that two Porto players were in offside positions, and obstructing Vaclik's view, when Casemiro scored.

Tello then broke down the right to fire in a shot that Vaclik pushed aside at the near post, and Martinez lifted a lob over the advancing keeper and the crossbar after turning into space from Oliver Torres' pass.

But Julen Lopetegui's side were good value for their equaliser, which came after Samuel handled Danilo's cross, and will be favourites to go through when the teams meet in Portugal for the second leg on 10 March.

Basel coach Paulo Sousa: "All my players can play better than we did tonight. We are much better than what we've shown tonight.

"We hoped to give Porto problems, and it worked at first - but we can do a lot better."

Porto coach Julen Lopetegui: "They scored with their only shot on target while we had many shots on target.

"I think we deserved an even better result than this. We showed quality and spirit against a team that, in this stadium, had already been superior to Liverpool and Real Madrid."