CINCINNATI — All Cincinnati manager Dusty Baker can do is hope his reeling Reds learn from their mistakes.

Rookie Drew Sutton’s defensive lapse in he eighth inning allowed Josh Willingham to hustle home from third base with the winning run as the Washington Nationals rallied for a 5-4 win over the Reds on Sunday.

Sutton — playing second base in place of the injured Brandon Phillips — allowed the go-ahead run to score from third when he lobbed a relay throw to first baseman Joey Votto behind the mound on pinch-hitter Ryan Zimmerman’s hit.

‘‘That wasn’t a very heads-up play,’’ Baker said. ‘‘You hope it doesn’t happen again.’’

It was the Reds’ third straight loss to the team with baseball’s worst record and their 14th in 22 games since the All-Star break.

Leading 4-3 with one out in the eighth inning, Arthur Rhodes (0-1) came on to face slugger Adam Dunn. Rhodes brushed Dunn with a pitch, and Josh Willingham followed with a single to right — his third hit of the day.

‘‘He barely hit Dunn, and Willingham’s hot,’’ Baker pointed out. ‘‘I thought we were going to get out of the inning.’’

One out later, Zimmerman pinch hit for Alberto Gonzalez and lofted a bloop single to short right field, just under the glove of a diving Chris Dickerson — in as a defensive replacement.

Dunn scored as the ball rolled free, and Willingham took off from third when Sutton softly tossed a throw to Votto behind the mound. Votto’s throw home was high and Willingham ran into leaping catcher Ryan Hanigan as he gave Washington a 5-4 lead.

‘‘I looked at third, and I thought I saw him break down and stop,’’ Sutton said. ‘‘I guess he didn’t break down as much as I thought. I didn’t lob it, but I didn’t throw it, either. That was completely my fault. I’ve got to make sure the guy stops.’’

Willingham didn’t surprise Washington manager Jim Riggleman at all.

‘‘He’s just a ballplayer,’’ Riggleman said. ‘‘The winning run was all him. You can’t teach that. He saw a chance to do something. With two outs, that’s a good situation to try that.’’

Reds’ boxscore

Sunday’s Game

Nationals 5, Reds 4

Washington Cincinnati

ab r h bi ab r h bi

Morgan cf 5 0 0 0 Tavers cf 5 0 1 0

CGzmn ss 5 0 0 0 Sutton 2b 4 1 0 0

Bellird 3b-2b 4 0 0 0 Votto 1b 5 1 2 1

Dunn 1b 2 3 2 0 Gomes rf 4 1 2 3

Wlngh lf 4 2 3 3 Masset p 0 0 0 0

Dukes rf 4 0 0 0 Rhodes p 0 0 0 0

AlGnzlz 2b 3 0 0 0 L.Nix rf 0 0 0 0

Zmrmn 3b 1 0 1 1 Balentn lf 3 0 0 0

Nieves c 4 0 3 0 ARosls 3b 3 0 0 0

MacDgl p 0 0 0 0 Janish ss 4 0 1 0

Lannan p 2 0 0 0 Hanign c 4 1 1 0

Bergmn p 0 0 0 0 Lehr p 2 0 1 0

WHarrs ph 1 0 0 0 Burton p 0 0 0 0

Sosa p 0 0 0 0 Herrer p 0 0 0 0

J.Bard c 1 0 0 0 Dickrsn rf 1 0 0 0

Fisher p 0 0 0 0

Totals 36 5 9 4 Totals 35 4 8 4

Washington 000 201 020 — 5

Cincinnati 000 040 000 — 4

E–Belliard (4), A.Rosales (5). LOB–Washington 6, Cincinnati 8. 2B–Dunn 2 (25), Willingham (25), Lehr (1). HR–Willingham (19), Gomes (15). SB–Taveras (25). CS–Willingham (3). S–Lehr.

IP H R ER BB SO

Washington

Lannan 5.2 7 4 4 3 2

Sosa W, 2-1 1.2 1 0 0 0 1

Bergmann 0.1 0 0 0 0 1

MacDougal S,13-14 1.1 0 0 0 0 1

Cincinnati

Lehr 6.0 6 3 3 0 2

Burton H,5 0.1 1 0 0 0 0

Herrera H,6 0.2 0 0 0 0 1

Massett H,9 0.1 0 0 0 0 0

Rhodes L0-1, BS 1-1 0.2 2 2 2 0 0

Fisher 1.0 0 0 0 0 1

HBP–by Rhodes (Dunn), by Lehr (Dunn). WP–Lehr. Umpires–Home, Angel Campos; First, Tim McClelland; Second, Andy Fletcher; Third, Greg Gibson. T–3:04. A–18,030 (42,319).