Portuguese football agent Jorge Mendes believes Arsenal took too long to decide on signing Cristiano Ronaldo, allowing Manchester United to snap up the winger.
Ronaldo, who now plays for Real Madrid, joined the Red Devils in 2003 from Sporting Lisbon after being watched on numerous occasions by Arsenal.
The 27-year-old's agent Mendes believes the Gunners were too slow to act and that allowed Sir Alex Ferguson to capture Ronaldo.
"I remember what happened to Ronaldo at Arsenal," he said. "They watched him nine or ten times, and when everything seemed decided, then Manchester United played at the inauguration of the Alvaladze Stadium (Sporting Lisbon) and the players themselves urged Ferguson to buy him.
"Nani was also followed by Tottenham and Arsenal, but as I say, who sleeps in business loses."
And Mendes insists that data compiled by some of Europe's biggest sides such as Inter Milan, Liverpool and Arsenal for potential new signings are the way forward.
"Of course games are important in this regard," stressed Mendes. "The champions in each country provide data critical to hiring players.
"At the beginning of each season, some of the biggest European clubs set a schedule to examine these challenges."