Forwards Spencer Machacek and Joey Crabb potted goals for Chicago (45-20-1-5), which became the first West Division team to secure a playoff berth earlier in the week. Wolves goaltender Drew MacIntyre (19-15-1) made 27 saves in the losing effort.
Peoria (34-29-2-6) opened scoring 3:57 into the first period. MacIntyre made an initial save but coughed up the rebound and lost sight of it, allowing right wing Pascal Pelletier time to move in and knock it into the net.
The Wolves pulled even with 1:29 left to play in the first frame with a power-play tally from Machacek, who shoveled the rebound from a Jamie Hunt shot past Peoria goaltender Ben Bishop to make the score 1-1.
Bishop (20-16-3) posted 23 saves for the Rivermen.
Peoria regained the lead, 2-1, just 2:28 into the second period. Right wing Adam Cracknell took a pass from left wing Chris Porter in the right face-off circle and ripped a shot past MacIntyre.
Peoria padded their lead, 3-1, when a long blast from center Lars Eller beat MacIntyre at 11:28 of the third period.
The Wolves fought back to make the score 3-2 with five minutes left in the final frame when Crabb carried the puck down the left side of the ice and ripped a backhanded shot up over Bishop’s shoulder, but an empty net tally with 30 seconds left in the game iced the win for Peoria, 4-2.
The Wolves return home to host the Texas Stars at the Allstate Arena on Friday at 7:30 p.m.
Chicago 1 0 1 -- 2
Peoria 1 1 2 -- 4
First Period---1, Peoria, Pelletier 16 (Junland, Armstrong), 3:57; 2, Chicago, Machacek 18 (Hunt, Pohl), 18:31 pp. Penalties---Postma, Chicago (interference), 1:47; Guenin, Peoria (interference) 5:57; McIlvane, Peoria (tripping), 11:45; Weller, Chicago (interference), 15:11; Tallackson, Peoria (goaltender interference), 16:32.
Second Period---3, Peoria, Cracknell 14 (Porter, Paddock), 2:28. Penalties---Kaip, Chicago (tripping), 4:53; Love, Peoria (hooking), 11:53; Guenin, Peoria (holding), 14:21; Stewart, Chicago (roughing), 18:28; Armstrong, Peoria (slashing), 18:28.
Third Period---4, Peoria, Eller 15 (Armstrong, Porter), 11:28; 5, Chicago, Crabb 23 (unassisted), 15:00; 6, Peoria, Guenin 4 (unassisted), 19:30 en/sh. Penalties---Strachan, Peoria (high-sticking), 17:38.
Shots on goal---Chicago: 11-10-4--25. Peoria: 11-10-10--31. Power plays---Chicago: 1-6. Peoria: 0-3. Goalies--Chicago, MacIntyre (27-30). Peoria, Bishop (23-25). A---5,002. Referee---Kyle Rehman. Linesmen---Dan Cohen and Judson Ritter.