Atletico Madrid manager Diego Simeone has reportedly been left furious at Arsenal's deadline-day move for Thomas Partey.

The Gunners have been heavily linked with the 27-year-old throughout the summer transfer window but have waited until the closing hours to make their move, triggering his €50m (£45.4m) release clause this afternoon.

Thomas has now passed the first part of his medical and is understood to be on the verge of completing a deal which will see him sign a five-year contract at the Emirates Stadium.

Spanish outlet Libertad Digital reports that the developments have taken Simeone completely by surprise, with the Argentine boss sure Thomas was going to stay at the club.

The report claims that Simeone had been talking to impending arrival Lucas Torreira about a midfield partnership with Thomas ahead of the Uruguayan's separate move from Arsenal.

Official confirmation of Torreira's move to the Wanda Metropolitano is expected in the coming hours, while Thomas is also expected to complete his switch before tonight's 11pm deadline.