It was a comeback 16 months in the making.It lasted just 22 minutes.But Socceroo Vinnie Grella has no regrets about attempting his ill-fated return to the field with A-League club Melbourne Heart.As with most things in a career highlighted by a decade in Italy's Serie A and two World Cup finals campaigns, Grella didn't die wondering."I've tried and left no stone unturned. It's been frustrating because I'm a competitor, and I've always tried to compete at the top level as often as possible," Grella said on Tuesday."Ending in this way, not because of a lack of passion or lack of enjoyment, but a physical problem which doesn't allow you to compete any more, that leaves a bitter taste in my mouth."But I enjoyed so much the good times. Now I've just got to accept my time's up."Grella's retirement at 33 ends the career of a Socceroo who was the fiercest of competitors, the most honest of speakers, and the hardest of workers for his country.Raised in Melbourne, Grella played at an Olympic Games and two World Cup finals among 46 appearances for Australia.He and great friend Mark Bresciano - whom Grella rates the best player he ever played with - gave Australia a decade-long presence in the Serie A at a time it was the world's best club competition before a move to England's top-flight.Until the Heart match, he had not taken the field in a top-level game since September 2011, when he played for English Premier League club Blackburn Rovers.Grella admits his calf gave way just three minutes after entering Heart's match on Saturday night as a 68th minute substitute - the latest and last in his two-and-a-half year struggle with calf, knee and groin problems.He kept playing despite the pain, aware in his own mind this was the final signal his time was up after such a meticulous process of rehabilitation wasn't able to get his body right.For his career highlights, two matches stand out."The game against Uruguay in Sydney (in which the Socceroos achieved 2006 World Cup finals qualification) was the biggest and most enjoyable game of my career, and the first game in Italy (in the Serie A) which was a childhood dream," he said.Grella is unsure what his next career move will be - saying he is still "shellshocked" at the thought of retirement.First will be what he calls a "three-month breather" - returning to Italy to catch up with wife Barbara, 11-year-old twins Sophia and Victoria and 11-month-old son Eduardo.Grella and his family will remain based in Italy, and he says he wants to remain involved in the game post-retirement.