# 1985 Japan Open Tennis Championships – Men's singles

David Pate was the defending champion, but lost in the third round to Jonathan Canter.
Scott Davis won the title by defeating Jimmy Arias 6–1, 7–6$^{(7–3)}$ in the final.

## Seeds

* Tim Mayotte (third round)
* Scott Davis (champion)
* David Pate (third round)
* Jimmy Arias (final)
* Greg Holmes (quarterfinals)
* Sammy Giammalva Jr. (quarterfinals)
* Vitas Gerulaitis (first round)
* Robert Seguso (third round)
* Ken Flach (third round)
* Huub van Boeckel (first round)
* Matt Anger (quarterfinals)
* Jonathan Canter (quarterfinals)
* Vincent Van Patten (third round)
* Glenn Michibata (semifinals)
* Russell Simpson (third round)
* Menno Oosting (second round)

## Draw
### Key

* Q = Qualifier
* WC = Wild card
* LL = Lucky loser
* Alt = Alternate
* SE = Special exempt
* PR = Protected ranking
* ITF = ITF entry
* JE = Junior exempt
* w/o = Walkover
* r = Retired
* d = Defaulted
* SR = Special ranking

### Finals

| Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Semifinals | Semifinals | Semifinals | Semifinals | Semifinals | Final | Final | Final | Final |
| 14 | Glenn Michibata | 6 | 6 | | | | | | | | | | |
| 5 | Greg Holmes | 4 | 4 | | | | | | | | | | |
| 5 | Greg Holmes | 4 | 4 | | 14 | Glenn Michibata | 7 | 3 | 4 | | | | |
| | | | | | 4 | Jimmy Arias | 5 | 6 | 6 | | | | |
| 4 | Jimmy Arias | 6 | 6 | | 4 | Jimmy Arias | 5 | 6 | 6 | | | | |
| 11 | Matt Anger | 3 | 3 | | | | | | | | | | |
| 11 | Matt Anger | 3 | 3 | | | | | | | 4 | Jimmy Arias | 1 | 6$^3$ |
| | | | | | | | | | | 2 | Scott Davis | 6 | 7$^7$ |
| | Johan Carlsson | 1 | 7 | 6 | | | | | | | | | | 2 | Scott Davis | 6 | 7$^7$ |
| 12 | Jonathan Canter | 6 | 6 | 1 | | | | | | | | | |
| 12 | Jonathan Canter | 6 | 6 | 1 | | Johan Carlsson | 4 | 1 | | | | | |
| | | | | | 2 | Scott Davis | 6 | 6 | | | | | |
| 6 | Sammy Giammalva Jr. | 4 | 2 | | 2 | Scott Davis | 6 | 6 | | | | | |
| 2 | Scott Davis | 6 | 6 | | | | | | | | | | |

### Top half
#### Section 1

| First round | First round | First round | First round | First round | Second round | Second round | Second round | Second round | Second round | Third round | Third round | Third round | Third round | Third round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals |
| 1 | T Mayotte | 6 | 6 | | | | | | | | | | | | | | | |
| | S Menon | 1 | 3 | | 1 | T Mayotte | 6 | 6 | 6 | | | | | | | | | |
| Q | C Stansbury | 6 | 6 | | Q | C Stansbury | 7 | 0 | 1 | | | | | | | | | |
| | S Shiraishi | 2 | 0 | | | | | | | 1 | T Mayotte | 6 | 6 | 4 | | | | |
| Q | Shoichi Tatsuno | 4 | 1 | | | | | | | 14 | G Michibata | 7 | 4 | 6 | | | | |
| | B Dickinson | 6 | 6 | | | B Dickinson | 1 | 3 | | | | | | | | | | |
| | S Guy | 2 | 4 | | 14 | G Michibata | 6 | 6 | | | | | | | | | | |
| 14 | G Michibata | 6 | 6 | | | | | | | | | | | | 14 | G Michibata | 6 | 6 |
| 10 | H van Boeckel | 6 | 4 | | | | | | | | | | | | 5 | G Holmes | 4 | 4 |
| | C Dunk | 7 | 6 | | | C Dunk | 6 | 2 | 6 | | | | | | | | | |
| | Minoru Ueda | 7 | 3 | 3 | | C Campbell | 4 | 6 | 3 | | | | | | | | | |
| | C Campbell | 5 | 6 | 6 | | | | | | | C Dunk | 2 | 4 | | | | | |
| | G Lemon | 6 | 6 | | | | | | | 5 | G Holmes | 6 | 6 | | | | | |
| Q | S Matsuoka | 3 | 4 | | | G Lemon | 2 | 1 | | | | | | | | | | |
| | S Denton | 7 | 6 | 5 | 5 | G Holmes | 6 | 6 | | | | | | | | | | |
| 5 | G Holmes | 5 | 7 | 7 | | | | | | | | | | | | | | |

#### Section 2

| First round | First round | First round | First round | First round | Second round | Second round | Second round | Second round | Third round | Third round | Third round | Third round | Third round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals |
| 4 | J Arias | 6 | 6 | | | | | | | | | | | | | | |
| | R Brown | 2 | 4 | | 4 | J Arias | 7 | 6 | | | | | | | | | |
| | R Van't Hof | 6 | 3 | 6 | | J Manset | 6 | 1 | | | | | | | | | |
| | J Manset | 4 | 6 | 7 | | | | | 4 | J Arias | 3 | 7 | 6 | | | | |
| WC | T Tsuchihashi | 6 | 1 | 6 | | | | | 15 | R Simpson | 6 | 6 | 3 | | | | |
| | H Shirato | 2 | 6 | 3 | WC | T Tsuchihashi | 2 | 3 | | | | | | | | | |
| | E Takeuchi | 2 | 4 | | 15 | R Simpson | 6 | 6 | | | | | | | | | |
| 15 | R Simpson | 6 | 6 | | | | | | | | | | | 4 | J Arias | 6 | 6 |
| 11 | M Anger | 6 | 6 | | | | | | | | | | | 11 | M Anger | 3 | 3 |
| | T Mmoh | 2 | 0 | | 11 | M Anger | 6 | 7 | | | | | | | | | |
| | M Wooldridge | 4 | 4 | | | T Fukui | 3 | 5 | | | | | | | | | |
| | T Fukui | 6 | 6 | | | | | | 11 | M Anger | 6 | 6 | | | | | |
| | L Courteau | 6 | 6 | | | | | | 8 | R Seguso | 4 | 4 | | | | | |
| LL | Kenzo Ukon | 2 | 1 | | | L Courteau | 2 | 1 | | | | | | | | | |
| Q | T Sakai | 2 | 2 | | 8 | R Seguso | 6 | 6 | | | | | | | | | |
| 8 | R Seguso | 6 | 6 | | | | | | | | | | | | | | |

### Bottom half
#### Section 3

| First round | First round | First round | First round | First round | Second round | Second round | Second round | Second round | Second round | Third round | Third round | Third round | Third round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals |
| 7/WC | V Gerulaitis | 4 | 1 | | | | | | | | | | | | | | | |
| | J Carlsson | 6 | 6 | | | J Carlsson | 6 | 6 | | | | | | | | | | |
| | D Utzinger | 7 | 3 | 2 | | H Rittersbacher | 1 | 4 | | | | | | | | | | |
| | H Rittersbacher | 6 | 6 | 6 | | | | | | | J Carlsson | 6 | 6 | | | | | |
| | S Vasudevan | 6 | 6 | | | | | | | 9 | K Flach | 2 | 1 | | | | | |
| WC | Kazuya Morita | 1 | 0 | | | S Vasudevan | 6 | 4 | | | | | | | | | | |
| | J Bailey | 1 | 6 | 4 | 9 | K Flach | 7 | 6 | | | | | | | | | | |
| 9 | K Flach | 6 | 3 | 6 | | | | | | | | | | | J Carlsson | 1 | 7 | 6 |
| 12 | J Canter | 6 | 6 | | | | | | | | | | | 12 | J Canter | 6 | 6 | 1 |
| Q | Shōichi Horiuchi | 3 | 0 | | 12 | J Canter | 6 | 6 | | | | | | | | | | |
| | K Richter | 3 | 7 | 6 | | K Richter | 1 | 4 | | | | | | | | | | |
| | H McDadi | 6 | 5 | 3 | | | | | | 12 | J Canter | 7 | 6 | | | | | |
| | S McCain | 6 | 6 | | | | | | | 3 | D Pate | 5 | 2 | | | | | |
| LL | Kiyotaka Tachibana | 2 | 4 | | | S McCain | 3 | 7 | 4 | | | | | | | | | |
| | A Kohlberg | 6 | 2 | 3 | 3 | D Pate | 6 | 5 | 6 | | | | | | | | | |
| 3 | D Pate | 4 | 6 | 6 | | | | | | | | | | | | | | |

#### Section 4

| First round | First round | First round | First round | First round | Second round | Second round | Second round | Second round | Second round | Third round | Third round | Third round | Third round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals |
| 6 | S Giammalva Jr. | 7 | 6 | | | | | | | | | | | | | | |
| | E Van't Hof | 5 | 3 | | 6 | S Giammalva Jr. | 7 | 6 | | | | | | | | | |
| | R Nixon | 5 | 2 | | | G Donnelly | 6 | 3 | | | | | | | | | |
| | G Donnelly | 7 | 6 | | | | | | | 6 | S Giammalva Jr. | 6 | 7 | | | | |
| | R Rudeen | 6 | 6 | | | | | | | | R Rudeen | 4 | 6 | | | | |
| | D Saltz | 3 | 0 | | | R Rudeen | 6 | 6 | 6 | | | | | | | | |
| WC | T Yonezawa | 3 | 7 | 4 | 16 | M Oosting | 7 | 2 | 4 | | | | | | | | |
| 16 | M Oosting | 6 | 5 | 6 | | | | | | | | | | 6 | S Giammalva Jr. | 4 | 2 |
| 13 | V Van Patten | 6 | 6 | | | | | | | | | | | 2 | S Davis | 6 | 6 |
| WC | H Nakano | 2 | 3 | | 13 | V Van Patten | 7 | 7 | | | | | | | | | |
| Q | Takeshi Murakami | 0 | 2 | | | A El-Mehelmy | 6 | 5 | | | | | | | | | |
| | A El-Mehelmy | 6 | 6 | | | | | | | 13 | V Van Patten | 4 | 4 | | | | |
| Q | S Nishio | 4 | 4 | | | | | | | 2 | S Davis | 6 | 6 | | | | |
| Q | Hajime Nihonmatsu | 6 | 6 | | Q | Hajime Nihonmatsu | 0 | 0 | | | | | | | | | |
| | C Strode | 3 | 2 | | 2 | S Davis | 6 | 6 | | | | | | | | | |
| 2 | S Davis | 6 | 6 | | | | | | | | | | | | | | |