| Koji Watanabe | |
| Birth Date: | 1942 1, df=yes |
| Birth Place: | Ashiya, Hyogo, Japan |
| Turnedpro: | 1961 (amateur tour) |
| Retired: | 1971 |
| Singlesrecord: | 165-21 (88.7%) [1] |
| Singlestitles: | 4 [2] |
| Australianopenresult: | 2R (1965), (1969) |
| Frenchopenresult: | 2R (1964), (1966) |
| Wimbledonresult: | 2R (1969) |
| Team: | yes |
is a Japanese former international tennis player. He won four career singles titles (1966–1969).
Watanabe played his first tournament at the Miami Invitational in 1961.[3] He won his first title on clay at Gruneweld, West Germany in August 1966 beating compatriot Ichizo Konishi in three sets.[3] In 1966 he claimed his second title again on clay at Ostend, Belgium defeating South African player Jackie Saul two sets to one.[3] His third title came in 1968 at the Lowther Hard Court Championships, Barnes, London where he beat New Zealand player Onny Parun two sets to one.[3] His fourth and final tile came in 1969 at the Athens International on clay where he defeated Australian player Geoff Masters three sets to one.[3] He reached the finals of three other tournaments Andhra Pradesh Championships on hard courts in (1966), the Worcestershire Championships, on grass in (1967) and finally Bad Neuenahar on clay in (1969).[3] In Grand Slam tournaments he competed in the Australian Open two times, in 1965 and 1969.,[4] [5] The French Open in 1964 and 1966 and at Wimbledon one time in 1969. He also served as coach for Japan's Davis Cup team (1971–1974) and as vice-chairman of the Japan Tennis Association.
He played his last tournament at the Tokyo Indoor in 1971 losing to Ian Fletcher in the semifinals.[3]