Arsenal issued a complaint to UEFA ahead of their crucial Champions League semi-final against Atletico Madrid over the length of grass at the Spanish club's stadium.

Approximately two hours before kick-off in Madrid, the Gunners' ground staff took issue with the turf at Riyadh Air Metropolitano and asked UEFA to measure the length of the grass, claiming it was too high. 

After reviewing the pitch, European football's governing body concluded that the turf was legal as the grass was only 26millimetres in length, the same as when they faced Barcelona at the stadium during the quarter-finals.

Much has been speculated over the tactics both Atletico Madrid manager Diego Simeone and Arsenal boss Mikel Arteta will deploy during the intriguing Champions League semi-final tie, with so much at stake for the team who comes out on top.

Both Simeone and Arteta have established a reputation for finding any way possible to steal a edge on their opponents, whether that be jostling from corners or subtle acts of gamesmanship. 

And Arsenal were concerned that Atletico were trying to gain an advantage by growing out the grass, which - if too long - would slow down the speed of the ball across the turf. 

Guillem Balague told CBS Sports: 'I need to tell you about the grass war that took place just about an hour ago because Arsenal’s ground staff came in thinking the grass is too high. They were not happy with it. 

'They asked Uefa to actually measure it. They weren’t happy, they thought that it was Simeone creating some dark arts.

'After a while Uefa said no, it’s actually 26mm. The limit is 30mm and it goes between 21mm and 30mm.

'It’s 26mm which, by the way, was the same when they played Barcelona here.'

Italy and Juventus legend Alessandro Del Piero admitted it was a shame that 'grass wars' had put a dampener on the semi-final ahead of kick-off. 

He urged that Simeone's side are blessed with a rich array of talented stars in attack, such as Antoine Griezmann and Julian Alvarez, and that it would be in Atletico's interest to have the pitch in top condition.

'The pitch is key for them (Atletico),' he said. 'I don't like it when there are too many rumours about this stuff. I'm worried about Arsenal and Arteta bringing it up to be honest.  

'It is a great picture of Arsenal at the moment. They are struggling a little bit and are having to have a look at every detail.'

Tottenham struggled to manage Atletico Madrid's pitch when they visited the Riyadh Air Metropolitano during their round of 16 tie. 

Antonin Kinsky made two costly errors to gift Simeone's side a colossal advantage, while Micky van de Ven also slipped on the turf.