Harry Redknapp's excuses for his £180,000 offshore windfall are "contradictory, inconsistent and lack credibility", a court heard on Wednesday.
Jurors were asked to consider how the Tottenham Hotspur manager "simply laughed" when questioned about the Monaco "bung".
Prosecutor John Black QC completed his opening speech by pointing out how Redknapp's story differed from co-defendant Milan Mandaric's.
"Those explanations, the Crown say, are contradictory, inconsistent and lack credibility," Mr Black said.
Mr Black said: "At the heart of the Crown's case is the fact that no tax was paid."
Both payments were employment related and were therefore taxable, Mr Black added.
"You may think in this case there can be no doubt that these payments constitute bonus payments paid while he was manager at Portsmouth," Mr Black told Southwark Crown Court.
Mandaric was determined to "maintain the goodwill" of a talented manager, Mr Black added.
"He was a prime candidate to be poached by other clubs and in the event that was what transpired," the barrister added.
Jurors were asked to consider, "is it credible that Mr Redknapp remained blissfully unaware" of the deposits in the account named after his pet dog, Rosie.
Mr Black also pointed to evidence that Redknapp "simply laughed about it and decided to forget about it all".
Referring to police interviews with Mandaric, Mr Black asked "is there any credibility, you might like to consider" that the payments "constituted a loan".
Mr Black said: "Why, in that case, was Mr Redknapp under such misapprehension?"
Redknapp claimed he "received express reassurances from Mr Mandaric that the tax had been paid", while Mandaric "assumed that Mr Redknapp would take legal advice and make the necessary action".
Both Redknapp and Mandaric deny two counts of cheating the public revenue when Redknapp was manager of Portsmouth Football Club.
The first charge of cheating the public revenue alleges that between April 1, 2002 and November 28, 2007 Mandaric paid 145,000 US dollars (£93,100) into the account.
The second charge for the same offence relates to a sum of 150,000 US dollars (£96,300) allegedly paid between May 1, 2004 and November 28, 2007.