Kevin Nolan told the jury he had passed the details of a hamper salesman named "Mark Kingston" to club officials.
Stephen Ackerman is accused of selling hampers to players that never arrived under the alias Mark Kingston.
The 48-year-old, of Loughton, Essex, denies 19 fraud charges with the proceeds totalling more than £60,000.
Mr Nolan told Snaresbrook Crown Court he was the given the details of "a fella called Mark" by nightclub manager Scott Cummings.
The 34-year-old said he passed the details to player liaison officer Tim De'Ath telling him: "Mark sold luxury hampers and he would like to come into the training ground."
When asked by prosecutor Richard Milne if he was a "sort of a middleman", Mr Nolan replied "yes".
The former Leyton Orient boss said he paid £920 for two Harrods hampers and 25 bottles of champagne from a salesman who was in his mid-40s, had dark hair, and wore a grey flat cap.
However, he said he never received the items.
Former West Ham defender Joey O'Brien told the court he had paid £1,200 for two hampers and some rose champagne, but noticed two extra payments totalling £780 were also taken.
"I did not know anything about those on my bank statement until I checked," he said.
He described the salesman as "smartly dressed" and wearing a "smart watch".
Tim De'Ath, who has previously picked out Mr Ackerman in an identity parade, told the court he was not embarrassed about arranging for the salesman to come to the club.
"It was Mr Nolan that told me to get him in," he said.
When questioned by defence counsel Michael Gumulka about whether he could have mistaken Mr Ackerman for another man, Mr De'Ath answered: "I disagree with that 100%."
The defence argues that Mr Ackerman was not the man who purported to be Mark Kingston.
The trial continues.
West Ham's former captain acted as an inadvertent "middleman" in a Christmas hamper con in which fellow players lost thousands of pounds, a court has heard.