Harris was a member of the Chelsea side which won the
FA Youth Cup in 1961 and made his senior club debut in February 1962 in a 1–0 win against
Sheffield Wednesday. Within a year, he had established himself as a regular in the side, a position he would hold for the next eighteen years. He formed an important part of new Chelsea manager
Tommy Docherty's youth-oriented re-building of the club after
relegation from the
First Division alongside the likes of
Peter Bonetti,
Peter Osgood and
Bobby Tambling. Upon the club's return to the top division, Harris solidified his reputation as an uncompromising – yet talented – defender with a series of strong (and sometimes notorious) performances. His first honours with Chelsea came with a
League Cup win over
Leicester City in
1965. In the same season, Chelsea were challenging for the league title for most of the year but ultimately finished third after winning just one of their final five matches. He became club
captain the following year when
Terry Venables left for
Tottenham Hotspur and became the youngest ever captain to lead out a side in the
1967 FA Cup Final, although they lost 2–1 to Tottenham. Chelsea, led by Harris, reached another FA Cup final three years later, this time against
Leeds United – a side then at their peak in English football. He won four caps for
England U23 between 1966 and 1968. That
1970 FA Cup Final is notorious for being one of the most physical of all time, it saw Harris come into his own in the role of both inspirational leader and uncompromising tackler. With Leeds having taken a 2–1 lead at
Wembley with just six minutes remaining, it was his quick
free kick which led to
Ian Hutchinson's headed equaliser to take the game to a replay. During the replay at
Old Trafford his late tackle on Leeds' playmaker
Eddie Gray after just eight minutes (just one of many late tackles committed by both sides), left the latter a virtual passenger for the rest of the match: Chelsea eventually won 2–1 after extra-time. The following season saw Harris lift Chelsea's first major
European honour – the
UEFA Cup Winners' Cup – in another replayed final against
Real Madrid in
Athens. Chelsea also reached a second League Cup final in 1972, but surprisingly lost to
Stoke in what proved to be his last major final for the club. ==Moves==