Michael Owen is on the verge of joining English champion Manchester United, a striking reversal of fortunes for an injury-plagued striker that many lower tier clubs had dismissed as past his best. United manager Sir Alex Ferguson, however, is willing to take a “calculated gamble,” as United’s web site says. The former Real Madrid and Liverpool player spent Friday at the Premier League champion’s Carrington training complex and a Manchester hospital for final medical examinations on his troublesome right knee.