Fontenot hit a tiebreaking two-run single with two outs in the fifth inning to back Marshall and lift the Cubs to a 3-2 victory over the Mariners and even the Interleague series.
The Cubs entered Wednesday's game batting .203 with the bases loaded, the worst in the National League. They had left the bases loaded in three innings in Tuesday's 4-3, 13-inning loss to the Mariners.
In the fifth on Wednesday, the Cubs loaded them up against Miguel Batista (7-5) when Derrek Lee singled, Mark DeRosa walked, and Ryan Theriot was safe on a throwing error by shortstop Yuniesky Betancourt. Fontenot then singled to right, driving in two.
"I'm trying to stay with the same approach, I'm not trying to change anything," Fontenot said. "Maybe I need to be a little more selective -- I've swung at a few pitches up in the zone. But I've been swinging the bat pretty well."
Marshall (3-2) was the beneficiary. The lanky left-hander posted his fifth straight quality start, giving up two runs on seven hits over a career-high eight innings. Marshall did serve up Richie Sexson's 10th home run leading off the Seattle second.
"I guess that's how you win ballgames, and how you're supposed to pitch," Marshall said of his quality starts. "I felt good out there, I felt comfortable. I just have to keep building and keep learning and keep doing it."
Marshall was slowed this spring by fatigue in his left shoulder and did not pitch at all in Cactus League games.
"I was just behind schedule," Marshall said. "I knew it was just a matter of time before I caught up to the guys here in Chicago."
He's not only caught up, he's passed a few.
"Tonight, he was really exceptional," Cubs manager Lou Piniella said.
When you don't walk anyone and throw 94 pitches and give the bullpen a much-deserved breather, you'll get comments like that from the manager.
Hill also received kudos from Piniella for calling a good game. The catcher, who had appeared in 50 big-league games with the Dodgers and Diamondbacks before this year, has been working on building trust with the pitchers since he was called up June 1.
"That's my job," Hill said. "I stand out in the outfield, and talk to them about pitching. I'm here for them. I want them to feel as comfortable with me as they have with anybody, and know they can throw the ball anywhere they want and I'll do whatever I can to block it or catch it."
The Cubs are 4-1 with Hill behind the plate instead of Michael Barrett. Don't read anything more into that.
"I'm his caddy," Hill said of Barrett. "I'll be out there whenever he's not. Me and Mike have a great relationship, a great one. He's been like a brother to me. We talk a lot, we sit next to each other on the bench. He's been nothing but a big brother to me. I'm here to do one job, and that's to get these guys to win. It's not stealing anything from him."
Marshall had thrown to Hill at Iowa earlier this year and has thrown to Barrett as well.
"Both Michael and Koyie have been really good," Marshall said. "I give [Hill] a lot of credit -- I didn't shake him off maybe two or three times, and when I did shake him off, I gave up a base hit. I love throwing to both of these guys."
Did Marshall shake off Hill during Sexson's at-bat in the second?
"It was just a bad pitch," Marshall said. "I don't remember -- but probably."
Ryan Dempster notched a 1-2-3 ninth for his 14th save in 16 opportunities, and second in the last three days.
This is the Mariners' first trip to Wrigley Field, and the series now is tied at one win apiece with the rubber game Thursday.
After Sexson's homer, the Cubs tied the game with one out in the third when Felix Pie walked, reached third on Lee's single and scored on Cliff Floyd's groundout. Pie's baserunning is something the Cubs need, one of the little things that go unnoticed in the box score.
Fontenot's average can't be overlooked. He's hitting .429 in seven games so far.
"It's still the game of baseball," Fontenot said. "We take that kind of look at it. It's the same game we've played -- you just have to get over the fans and media things, and once you get comfortable, it's kind of fun."
Carrie Muskat is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.