Lionel Messi and Argentina's World Cup dream remains alive but an indefatigable Croatia side inspired by the enduring brilliance of Luka Modric stands in their way in Tuesday's semi-final in Doha.Argentina have recovered from the shock of losing their opening game in Qatar to Saudi Arabia and made the last four with an exhausting win on penalties against the Netherlands at the end of a fractious quarter-final on Friday.Having been 2-0 up and cruising after 83 minutes, with Messi setting up one goal in sublime fashion and netting a penalty, they conceded twice late on and had to survive extra time before triumphing 4-3 in a shoot-out.Backed by an enormous contingent of travelling supporters who have brought the passion, noise and colour of Argentina's own stadiums to this World Cup, Messi and his teammates are starting to believe this really could be their year."We have balls, passion, heart and we are doing this for 45 million people," said goalkeeper Emiliano Martinez, and Argentina's optimism now has only increased after seeing great rivals Brazil go out in the last round.Now aged 35, this has been billed as Messi's last chance to win a World Cup, eight years on from Argentina's defeat in the final to Germany in Rio de Janeiro.He is determined to seize the chance and has already scored his first two goals in the knockout rounds of any World Cup, netting against Australia in the last 16 before his penalty against the Dutch.World Cup glory would complete a wonderful career for the seven-time Ballon d'Or winner, who is possibly the greatest club player ever.After years of being unfulfilled at international level he inspired Argentina to victory at last year's Copa America, but he knows there are no more dogged or durable