STEVEN GERRARD has rocked England by insisting next summer’s World Cup could be his last after admitting he could retire in 2013.<br /><br />The Liverpool captain will be 33 at the end of his current contract, when he says he wants to call time on his illustrious career as a one-club man.<br /><br />Midfielder Gerrard also admitted he twice thought about leaving Liverpool, particularly when tempted by Chelsea in 2005, but insists his future remains with the Anfield club. <br /><br />“I will be 33 at the end of my contract in 2013 and I don’t know if I will go any further,” Gerrard admitted. “If I do retire, then I will know that from the start to the end of my career I only had one club. And I don’t want to think about wearing any other shirt in the future.<br /><br />“I was close to leaving in the past, maybe twice, most notably in 2005. That year we were a long way off the Premier League title and Chelsea’s interest turned my head. It was a difficult moment for me. However, now when I look back I am very happy that I chose to stay here. It has given me real pride.”<br /><br />Meanwhile Liverpool are favourites to sign Portsmouth and England defender Glen Johnson. The Reds are reported to have had a £17m offer accepted for the right-back, who has also attracted interest from Chelsea and Manchester City.