Volquez, traded to San Diego in December, has pitched against the Reds just once this season, and he hasn't pitched at Great American Ball Park since last September. Volquez lasted seven innings against Cincinnati earlier this month, and he held the Reds to one run and five hits at PETCO Park.
The Reds swept the Padres in that series, and they're moving through perhaps their best stretch of the season. The Reds haven't lost since July 18, and they've held their opponent to three runs or fewer in eight of their last 10 games. Eight of Cincinnati's last 10 wins have been by three runs or fewer.
Volquez hasn't taken a loss this month and is coming off another solid outing Tuesday in San Francisco, where he threw seven innings and allowed just two runs on three hits.
"I had a better rhythm after the first inning," Volquez said after the game. "I really wanted to get ahead in the count, and I think I did that. ... And I stayed in the game."
Volquez again failed to tally the necessary run support for the win, but he did continue his stellar July, in which he is 1-0 with a 1.93 ERA in four starts.
He'll toe the rubber against former teammate Mike Leake, who is also coming off a successful outing Tuesday in Houston.
Leake (4-6, 4.12 ERA) threw eight innings -- the fourth time he's reached that mark this season -- allowing two runs on seven hits and walking just one.
A Reds run in the ninth secured Leake's fourth victory of the season.
Padres: Heating up in July
While San Diego still sits in fourth place in the National League West, the month of July has provided some brighter spots.
Despite Sunday's loss, the club is 14-10 in July and has won nine of 16 since the All-Star break, much of which manager Bud Black credited to a healthy lineup.
"We've played well, and I think it starts on a number of factors," Black said. "We got Carlos [Quentin] healthy and back in the lineup. Huston [Street] missed a month; he came back. Our middle-infield situation changed over; [Logan] Forsythe got healthy. That coincided with a couple guys bringing up their play offensively, and our defensive play picked up. So when you add all that up, it equates to more victories."
The Padres announced Sunday that they had agreed to a two-year contract extension with closer Huston Street.
The deal is worth $14 million -- $7 million in each of the next two seasons -- with a club option for 2015.
"It's an honor," Street said. "Some people might say it's a team-friendly contract. That's fine with me. I'm happy. It's friendly to me. It's going to be very friendly to me."
Street is 2-0 with a 0.91 ERA in 31 appearances while recording 17 saves this season.
Reds: Waiting on Votto
While the Reds have been hotter than ever even without superstar Joey Votto in the lineup, the club is anxiously awaiting the first baseman's return.
Votto had arthroscopic surgery to repair a meniscus tear in his left knee on July 17, and he is eligible to be activated from the disabled list Tuesday.
The former National League MVP, who was expected to miss three to four weeks, has yet to resume baseball activities, but head trainer Paul Lessard said Votto is making steady progress.
With pitcher Nathan Eovaldi making his Marlins debut Saturday, the Reds are now the only club in the Majors to have used just five starting pitchers all season.
That doesn't seem to be changing any time soon, but the order in the rotation may.
Reds manager Dusty Baker hinted that a rotation swap may take place in the near future, based on the catching tandem behind the plate.
Ryan Hanigan currently works three days in a row for Bronson Arroyo, Johnny Cueto and Mat Latos. Rookie Devin Mesoraco catches two straight days for Leake and Homer Bailey.
"That's not how we drew it up in the beginning," Baker said. "If I thought it was better, we'd have done it in the beginning. But with Cueto's finger [blister] and stuff that happened, you've got to change. Whenever it's convenient, we'll change it back."
With Cincinnati holding on to secure its 10th straight win Sunday, legendary Reds broadcaster Marty Brennaman will have to shave his head to hold up his end of a bargain made with bench coach Chris Speier earlier this season.
"I'm a man of my word," said Brennaman, the 2000 Ford Frick Award winner.
The Padres took three of four from the Reds earlier in July when Cincinnati visited San Diego in the final games of the first half of the season.