Expos || 0–12 || Mike Torrez (9–11) || Ken Brett (12–7) || None || 10,427 || 62–74 |- style="background:#fbb" | 137 || September 3 (1) || @ Mets || 0–5 || Jerry Koosman (12–14) || Steve Carlton (11–17) || None || see 2nd game || 62–75 |- style="background:#bfb" | 138 || September 3 (2) || @ Mets || 6–3 || Dick Ruthven (6–9) || Craig Swan (0–1) || Mac Scarce (10) || 30,748 || 63–75 |- style="background:#fbb" | 139 || September 4 || @ Mets || 1–7 || Tom Seaver (16–8) || Jim Lonborg (12–12) || None || 13,674 || 63–76 |- style="background:#fbb" | 140 || September 5 || @ Mets || 0–4 || Ray Sadecki (4–3) || Wayne Twitchell (13–8) || Tug McGraw (16) || 12,563 || 63–77 |- style="background:#fbb" | 141 || September 7 || Pirates || 8–10 || Bob Johnson (4–1) || Mac Scarce (0–6) || Ramón Hernández (7) || 15,233 || 63–78 |- style="background:#fbb" | 142 || September 8 || Pirates || 3–5 || Bob Moose (10–11) || Steve Carlton (11–18) || Dave Giusti (17) || 16,320 || 63–79 |- style="background:#bfb" | 143 || September 9 || Pirates || 8–7 || Mac Scarce (1–6) || Bob Johnson (4–2) || None || 14,356 || 64–79 |- style="background:#bfb" | 144 || September 11 || Mets || 6–4 || Jim Lonborg (13–12) || Jerry Koosman (12–15) || None || 8,159 || 65–79 |- style="background:#fbb" | 145 || September 12 || Mets || 2–3 || Jon Matlack (13–15) || Wayne Twitchell (13–9) || Tug McGraw (19) || 8,418 || 65–80 |- style="background:#fbb" | 146 || September 13 || Mets || 2–4 (12) || Tom Seaver (17–9) || George Culver (6–5) || Tug McGraw (20) || 8,194 || 65–81 |- style="background:#fbb" | 147 || September 14 || @ Expos || 2–3 || Chuck Taylor (2–0) || Steve Carlton (11–19) || None || 13,458 || 65–82 |- style="background:#fbb" | 148 || September 15 || @ Expos || 4–5 (10) || Tom Walker (7–5) || Mac Scarce (1–7) || None || 34,331 || 65–83 |- style="background:#fbb" | 149 || September 16 || @ Expos || 2–4 || Steve Renko (14–10) || Jim Lonborg (13–13) || None || 18,122 || 65–84 |- style="background:#bbb" | – || September 17 || @ Cubs || colspan=6 | Postponed (rain); Makeup: September 18 as a traditional double-header |- style="background:#bfb" | 150 || September 18 (1) || @ Cubs