The Tigers overcame a 4-0 deficit against Kansas City for the second straight game and earned their 10th consecutive win over the Royals this season.
Guillen drove a 1-2 pitch from Affeldt (4-6) down the line and over the left-field fence for his 11th homer.
"I wanted to be patient and put the ball into play," said Guillen, who hit a low curve.
Affeldt was disappointed but gave all the credit to Guillen.
"Threw the pitch I wanted to throw," he said. "He beat me on it."
"I was trying to mix up the Royals and Teahen with different pitches," Jones said. "I got lucky and snapped a fastball for the strikeout."
Detroit's Kenny Rogers, who got the start for the AL in this week's All-Star Game, lasted only four innings in his first outing following the break. He allowed five runs and six hits, walked one and struck out three in his shortest stint this season.
Royals' starter Mark Redman gave up four runs and five hits in five plus innings. He walked three and didn't strike out a batter.
But Kansas City tied it against Joel Zumaya in the eighth on DeJesus' two-out, bases-loaded double.
"You've just got to keep playing," Tigers' manager Jim Leyland said. "We fought back, gave it back to them and fought back again."
Kansas City jumped out to a 4-0 lead in the second.
Berroa singled in a run, and Teahen hit a three-run homer - his second shot in two nights and ninth of the season.
Detroit cut the lead in half in the third on Thames' two-out, two-run triple, but the Royals made it 5-2 in the fourth on Berroa's solo home run.
The Tigers pulled within two runs in the fourth on Monroe's two-out RBI double before Emil Brown's RBI single the next inning made it 6-3.
Detroit caught up with three in the sixth on a RBI double by Chris Shelton, a sacrifice fly by Curtis Granderson and an error by Berroa at short on Placido Polanco's grounder that allowed Shelton to score the tying run.
"Not much I can say," Kansas City manager Buddy Bell said. "Baseball, man. It's just hard to explain sometimes."
|Carlos Guillen prepares himself for the congratulatory beating after hitting a game winner. (AP)|
|Players of the Game|
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|Kansas City Royals|
|David DeJesus, CF||5||1||2||3||0||0||0||.304|
|Esteban German, LF||5||0||1||0||0||0||0||.336|
|Reggie Sanders, DH||5||0||1||0||0||2||3||.248|
|Emil Brown, RF||5||0||2||1||0||1||1||.282|
|Tony Graffanino, 2B||3||1||2||0||1||0||1||.277|
|Matt Stairs, 1B||3||1||1||0||2||1||2||.273|
|Angel Berroa, SS||5||3||2||2||0||0||4||.248|
|Mark Teahen, 3B||3||2||2||3||2||1||2||.271|
|John Buck, C||4||1||1||0||0||1||2||.244|
|2B - David DeJesus (14, Zumaya), Tony Graffanino (15, Rogers), Matt Stairs (12, Colon), Mark Teahen (8, Rogers)|
|HR - Angel Berroa (6, Rogers), Mark Teahen (9, Rogers)|
|SH - Tony Graffanino (4)|
|RBI - David DeJesus 3 (21), Emil Brown (44), Angel Berroa 2 (36), Mark Teahen 3 (34)|
|2-OUT RBI - David DeJesus 3 (11), Angel Berroa (22)|
|CS - Tony Graffanino (4, 3rd base by Rogers/Rodriguez)|
|Team LOB - 8|
|DP - Berroa-Graffanino-Stairs|
|E - Angel Berroa (10, misplayed grounder), Esteban German (5, misplayed grounder)|
|Kansas City Royals|
|Elmer Dessens (BS,5)||1.1||3||4||3||1||1||0||4.41|
|Jeremy Affeldt (L,4-6)||0.1||1||1||1||0||0||1||6.20|
|IBB - Guillen by Elmer Dessens|
|HBP - Guillen (by Mark Redman)|
|Pitches-Strikes - Mark Redman 88-51, Elmer Dessens 37-20, Ambiorix Burgos 23-17, Jeremy Affeldt 8-6|
|Ground Balls-Fly Balls - Mark Redman 5-9, Elmer Dessens 2-2, Ambiorix Burgos 1-3|
|Batters Faced - Mark Redman 23, Elmer Dessens 9, Ambiorix Burgos 7, Jeremy Affeldt 2|
|Placido Polanco, 2B||5||1||1||0||0||0||0||.280|
|Marcus Thames, LF||4||0||1||2||1||1||1||.297|
|Ivan Rodriguez, C||5||0||1||0||0||0||1||.306|
|Magglio Ordonez, RF||5||1||1||0||0||0||1||.309|
|Carlos Guillen, SS||2||4||1||1||2||0||0||.300|
|Brandon Inge, 3B||4||1||2||1||0||0||1||.227|
|Craig Monroe, DH||4||2||3||2||0||0||1||.253|
|Chris Shelton, 1B||3||1||1||1||1||1||2||.282|
|Omar Infante, CF||2||0||0||0||0||0||3||.255|
|a- Curtis Granderson, PH-CF||1||0||0||1||0||0||1||.278|
|a-hit a sacrifice fly for Infante in the 6th|
|2B - Craig Monroe 2 (19, Redman, Burgos), Chris Shelton (13, Dessens)|
|3B - Marcus Thames (1, Redman)|
|HR - Carlos Guillen (11, Affeldt)|
|SF - Curtis Granderson (4)|
|RBI - Marcus Thames 2 (37), Carlos Guillen (53), Brandon Inge (49), Craig Monroe 2 (44), Chris Shelton (43), Curtis Granderson (45)|
|2-OUT RBI - Marcus Thames 2 (11), Craig Monroe (18)|
|Team LOB - 6|
|Outfield Assists - Magglio Ordonez 1|
|DP - Guillen-Polanco-Shelton|
|E - Carlos Guillen (15, misplayed grounder)|
|Joel Zumaya (BS,3)||1||2||3||3||2||1||0||2.58|
|Todd Jones (W,2-5)||1||1||0||0||1||1||0||5.50|
|IBB - Teahen by Roman Colon, Stairs by Todd Jones|
|Pitches-Strikes - Kenny Rogers 76-47, Roman Colon 44-28, Joel Zumaya 33-20, Todd Jones 19-12|
|Ground Balls-Fly Balls - Kenny Rogers 5-3, Roman Colon 6-0, Joel Zumaya 2-1, Todd Jones 2-0|
|Batters Faced - Kenny Rogers 18, Roman Colon 13, Joel Zumaya 8, Todd Jones 5|
|Attendance - 38442|
|Game Time - 3:32|
|Temperature - 77|
|Umpires - Home - Gary Cederstrom, First Base - Kerwin Danley, Second Base - Jim Reynolds, Third Base - Tim Welke|