23‑Nov‑1981 | Manila | Clay | R32 | | | Jim Gurfein [USA] d. (4)Cahill | 6-0 RET | | | | | | | | | |
16‑Nov‑1981 | Bangkok | Carpet | R32 | | 46 | (6)Van Winitsky [USA] d. Cahill | 6-1 6-4 | | | | | | | | | |
9‑Nov‑1981 | Taipei | Carpet | R16 | 100 | 32 | (3)Paul Mcnamee [AUS] d. Cahill | 6-2 6-4 | | | | | | | | | |
9‑Nov‑1981 | Taipei | Carpet | R32 | 100 | | Cahill d. Sashi Menon [IND] | 6-4 6-7 6-2 | | | | | | | | | |
2‑Nov‑1981 | Hong Kong | Hard | R16 | | | Lloyd Bourne [USA] d. Cahill | 6-4 6-2 | | | | | | | | | |
2‑Nov‑1981 | Hong Kong | Hard | R32 | | 51 | Cahill d. (6)John Fitzgerald [AUS] | 7-5 6-1 | | | | | | | | | |
1‑Sep‑1981 | US Open | Hard | R16 | | 4 | (4)Jimmy Connors [USA] d. Cahill | 6-3 6-3 6-1 | | | | | | | | | |
1‑Sep‑1981 | US Open | Hard | R32 | | 12 | Cahill d. (12)Johan Kriek [USA] | 4-6 6-2 6-1 6-4 | | | | | | | | | |
1‑Sep‑1981 | US Open | Hard | R64 | | | Cahill d. Andrew Pattison [USA] | 6-4 6-1 7-6 | | | | | | | | | |
1‑Sep‑1981 | US Open | Hard | R128 | | | Cahill d. Steve Meister [USA] | 6-3 6-3 6-4 | | | | | | | | | |
17‑Aug‑1981 | Cincinnati | Hard | R32 | | 1 | (1)John Mcenroe [USA] d. (Q)Cahill | 6-3 6-0 | | | | | | | | | |
17‑Aug‑1981 | Cincinnati | Hard | R64 | | 53 | (Q)Cahill d. John Fitzgerald [AUS] | 6-4 7-6 | | | | | | | | | |
10‑Aug‑1981 | Cleveland | Hard | R32 | | 35 | (3)Stan Smith [USA] d. Cahill | 6-7 6-4 6-3 | | | | | | | | | |
3‑Aug‑1981 | Indianapolis | Clay | R64 | | 48 | (15)Mark Edmondson [AUS] d. Cahill | 6-2 6-1 | | | | | | | | | |
27‑Apr‑1981 | Nagoya CH | Hard | R16 | | | Matt Mitchell [USA] d. (3)Cahill | 6-1 6-2 | | | | | | | | | |
27‑Apr‑1981 | Nagoya CH | Hard | R32 | | | (3)Cahill d. Bruce Kleege [USA] | 6-7 7-6 7-6 | | | | | | | | | |
20‑Apr‑1981 | Tokyo CH | Clay | SF | | | (5)Roland Stadler [SUI] d. (4)Cahill | 6-4 7-5 | | | | | | | | | |
20‑Apr‑1981 | Tokyo CH | Clay | QF | | | (4)Cahill d. Jim Delaney [USA] | 6-3 6-2 | | | | | | | | | |
20‑Apr‑1981 | Tokyo CH | Clay | R16 | | | (4)Cahill d. Damir Keretic [GER] | 7-6 6-0 | | | | | | | | | |
20‑Apr‑1981 | Tokyo CH | Clay | R32 | | | (4)Cahill d. Warren Maher [AUS] | 4-6 6-3 6-0 | | | | | | | | | |
6‑Apr‑1981 | Kyoto CH | Clay | QF | | | (5)Matt Doyle [USA] d. (4)Cahill | 5-7 6-4 6-3 | | | | | | | | | |
6‑Apr‑1981 | Kyoto CH | Clay | R16 | | | (4)Cahill d. Tsuyoshi Fukui [JPN] | 6-3 6-4 | | | | | | | | | |
6‑Apr‑1981 | Kyoto CH | Clay | R32 | | | (4)Cahill d. Scott Mccain [USA] | 6-3 3-6 6-3 | | | | | | | | | |
23‑Feb‑1981 | Memphis | Carpet | R64 | | 88 | Andrew Pattison [USA] d. Cahill | 7-6 6-2 | | | | | | | | | |
19‑Jan‑1981 | San Juan | Hard | R32 | | | Cliff Skakle [USA] d. Cahill | 6-7 6-3 6-4 | | | | | | | | | |