West Ham United have been hit by a £7 million bill over unpaid fees for when Carlos Tevez and Javier Mascherano were at the club.
It is understood Joorabchian has written and taped evidence which will support his claim, which covers insurance and loan fees, plus other services.
The writ is another massive blow to the Hammers, who are also facing a claim for damages from Sheffield United, who were relegated from the Premier League last term.
The Blades launched their action after the decision by an independent commission to issue a £5.5m fine - instead of a points penalty - against West Ham for irregularities over the signing of Tevez and Mascherano.
Tevez was a massive hit at West Ham and his goal-scoring spree at the end of the season helped the club survive in the Premier League.
Tevez has since moved on to Manchester United while Mascherano is at Liverpool.
