Guzman has been rehabbing since undergoing Tommy John elbow ligament replacement surgery last August. Lieber allowed one unearned run and two hits while striking out three in two innings in his third and final rehab appearance with Class A Peoria on Saturday.
"I'll be ready to go [Monday] if they need me," Lieber said.
Bobby Dernier, the team's Minor League baserunning instructor, saw some of the candidates, including outfielder Felix Pie, who was hitting .287 with 10 home runs, 19 doubles, five triples, 11 stolen bases and 52 RBIs. Pie, who could be added after Iowa's playoff run, had three RBIs in Saturday's 10-4 win over Omaha.
"He's been playing well," Dernier said of Pie, who was the Cubs' starting center fielder on Opening Day. "I talked to [Iowa manager Pat Listach] and he said Pie seems to be getting ready and peaking at the right time. He knows what's ahead. Hoffpauir also."
Hoffpauir's stats at Iowa have had fans clamoring for his return. The left-handed-hitting first baseman/outfielder batted .387 in August with 12 home runs, 10 doubles and 39 RBIs. Since the All-Star break, he was hitting .366 with a .796 slugging percentage. For the season, Hoffpauir has a .362 average, with career highs of 25 homers, 34 doubles, and 100 RBIs.
"He's doing exactly what you're supposed to do to push your way in the door," Dernier said. "It could be this door or another door, who knows? He's a throwback. He could've played in 1910, and he'll play in 2010, and anywhere inbetween.
"He's an old-time guy, a good baseball player," Dernier said. "You could find a flaw if you want to, but you could find one in all of us. He's having just a great year."
Hill was hitting .275 in 113 games with 17 homers, 24 doubles and 64 RBIs, and this will be McGehee's first trip to the show. He was hitting .296 with 12 homers, 30 doubles and 92 RBIs in 133 games.
"It's always nice for those guys to get a taste of it," Chicago's Mark DeRosa said. "Some of them, I hope they're ready to come up and contribute because we need them."
The influx of youth should give the Cubs a boost as well as some fresh players for the final month. The three-game series against Houston is one of three remaining at Wrigley Field for the Cubs. They now are 51-21 at Wrigley Field, and will have to do well on the road to clinch that playoff spot.
Chicago did finish August 20-8, the most wins in any month since going 20-10 in August 1984. Dernier remembers that season. He was a catalyst as the Cubs won the East Division.
"I was a fourth- or fifth-year guy [in '84], and we had older guys and younger guys and good balance then, and we have that here," Dernier said. "The older guys have to keep reminding the younger guys where we're at right now, that this is what winning looks like. When you have that balance, guys who have been through it before, it works. We've got that going on now."
CHC: RHP Jason Marquis (9-7, 4.52 ERA)
Marquis looked like a frontline starter against the Pirates in his last outing Wednesday, when he threw seven scoreless innings, struck out three and walked none for his ninth win of the year. Catcher Henry Blanco said Marquis' repertoire was in full gear and his fastball had bite. The right-hander continues to give the Cubs plenty of innings. Only once this season has he been unable to pitch past the fourth. Marquis is 9-5 with a 5.22 ERA against the Astros in his career.
HOU: RHP Roy Oswalt (12-9, 4.11 ERA)
Oswalt recorded his 22nd win against the Reds in a 4-1 victory on Wednesday. He is 6-2 in his past 10 starts with a 3.02 ERA, averaging 5.7 strikeouts a game. Oswalt is 11-11 all-time against Chicago, losing his only game against the Cubs this season. He earned five runs on 10 hits in 6 2/3 innings.
Reliever Chad Gaudin was unavailable because of lower back pain. His status was day-to-day. ... DeRosa made his first appearance at shortstop this season. ... Carlos Marmol is on pace to become the first pitcher in big league history to allow fewer than four hits per nine innings with at least 50 innings pitched, according to the Elias Sports Bureau. Marmol is averaging 3.86 hits per nine. ... Reed Johnson ended August batting .397 in 22 games. ... Jeff Samardzija extended his scoreless innings streak to 14 1/3. ... The winner of the second annual "Baby Ruth Ultimate 7th-Inning Stretch Competition" will be announced before Monday's game and will sing "Take Me Out to the Ball Game" in the middle of the seventh. ... DeRosa (10-for-20) and Derrek Lee (15-for-57) hit Oswalt well, but Jim Edmonds is 11-for-48 (.229) and Alfonso Soriano is 5-for-28 (.179) against the right-hander. ... Sam Fuld homered for Double-A Tennessee in a 5-2 victory over Carolina. ... The Cubs' rookie league team in Mesa, Ariz., finished its season with a 13-14 record after a 7-6 loss to the Athletics' affiliate on Saturday.
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Official game notes
Tuesday: Cubs (Carlos Zambrano, 13-5, 3.53) vs. Astros (Brandon Backe, 9-12, 5.42), 7:05 p.m. CT
Wednesday: Cubs (Ryan Dempster, 15-5, 2.95) vs. Astros (Randy Wolf, 8-11, 4.73), 7:05 p.m. CT