The Cuban-born Marquez won the game with eight strikeouts and didn't give up a hit until the first pitch of the seventh and final inning.
Germany reached Monday's deciding game against Canada, with the winner booking a spot in the 2013 World Baseball Classic. The game will be played at 1 p.m. ET and will be streamed live on worldbaseballclassic.com.
Eight starters scored runs for Germany and seven drove in runs, led by Matt Weaver going 3-for-4 with a home run, two runs and four RBIs. Aaron Altherr homered, scored twice and drove in three, while Toby Gardenhire added three hits and Donald Lutz had two hits.
"What a great game that was to watch," said German manager Greg Frady As a manager, you just try to stay out of the way. Our German hero was Marquez. He has always come through, and he did again today."
"Last night, we were very disappointed [about losing to Canada]. But I knew we would come back. We took this game very seriously. The hitting was on point. Nothing we did surprised me today. It was a great victory for German baseball, and it's an honor to play against Canada for a spot in the World Baseball Classic."
Marquez admitted he was hoping to pitch in the final against Canada, but he was focused on the task at hand.
"The game was really important for us," Marquez said. "I knew that we had to win. I just did my best, and it worked out. The coach just told me we have to win to advance, and I did all I could."
The 37-year-old lefty, who plays baseball in Italy, recalled pitching a perfect game in the German Bundesliga in 2006.
"You just can't think about something like that. You just have to throw strikes," said Marquez.
Great Britain had reached Sunday's game against Germany by beating the Czech Republic, 12-5, on Saturday. But Germany was playing at another level.
"You guys saw it, it was kind of ugly. I was happy that the guys didn't give up in the end and lie down," said Sam Dempster, Great Britain's manager.
"We had a nice dream come true yesterday, and we woke up with a nightmare today."
Despite playing a four-hour contest against Canada that lasted until nearly midnight CEST the night before, the Germans did not come out flat for the 2 p.m. first pitch, scoring three runs in the top of the first inning.
The first three Germans got on base, and Dempster decided to take out his starting pitcher, Kyle Wilson, after one pitch to Lutz, Germany's cleanup hitter.
Greg Hendrix gave up an RBI single to Lutz before Altherr and Jake Shaffer both hit sacrifice flies for a 3-0 Germany lead.
Germany added two more runs in the second inning on Max Kepler's two-run single to center to push the advantage to 5-0.
Marquez mowed down the Great Britain hitters and was perfect through 3 2/3 innings until Lutz mishandled Steven Bumbry's grounder to first base.
The German bats continued to roar in the fifth, with four runs. Lutz, a Cincinnati Reds farmhand, reached on an error to start the frame and scored on Altherr's two-run home run to left field. Gardenhire -- a Triple-A middle infielder for the Minnesota Twins and the son of their big league manager, Ron Gardenhire -- drove in the other two runs with a double for a 9-0 cushion.
Germany tacked on a 10th run in the sixth on a sacrifice fly by Weaver before the host side added six more in the top of the seventh.
Great Britain reliever Estevenson Encarnacion loaded the bases with three hit batsmen -- the third coming with two outs. Mike Larson singled in two runs and Gronauer added an RBI single before Weaver blasted a three-run home run for a 16-0 lead.
With Marquez working on a no-hitter, Albert Cartwright jumped on the first pitch of the seventh inning and singled through the left side of the German infield.
"There were a couple of good hits, but our defenders were there," said Marquez. "And then they just hit the ball and there was no one there. And that's it."
Bradley Hubbert followed an out later with a single to center, and Cartwright came around to score on Kepler's fielding error in center to give Great Britain its lone run.
David Hein is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.