Petrov was signed in the summer of 1999 by John Barnes for a fee of £2.8 million. The teenager featured prominently in a season where he won the League Cup with Celtic, his second major honour and the first of many with Celtic. Despite the happy end to the season Petrov had a very hard time starting with the club. He was homesick and lonely at the start, and could not speak English. This was made worse by the manager playing him out of position at right back. Eventually, he improved his English by working in a friend’s burger van. This hard work and determination to fit in showed in his performances for the club.