The first touchdowns scored by Georgia Tech’s Patrick Skov and Marcus Marshall in last week’s 69-6 win over Alcorn State exemplify the different skills they bring, and the different headaches they can cause for opponents.

Skov looked like a fullback in an option offense, which of course he is. On second and goal at the 3-yard line, he lowered his head and pushed a helpless defender about 15 feet backward into the end zone.

Marshall looked like a graceful, fast tailback. On second and 28 on the 49-yard line, Marshall went up the middle. Instead of lowering his head and being satisfied with just a few yards, he found a hole, made a nifty and slight shift to the right, and then did the same move again to gallop for a 49-yard touchdown.

One brings the power. The other brings the speed. They combined for 256 yards, a school record for two B-backs under coach Paul Johnson, and five touchdowns. Not bad debuts.

“I think we build off each other pretty well,” Skov said. “I’m excited for the season for both of us.”

Johnson agreed, with his usual blend of matter-of-factness.

“They played exactly like I thought they would play going into the game,” he said. “That’s who they are. I mean, we’ve seen them practice for five weeks.”

Skov is the older of the two, a 23-year-old senior who transferred from Stanford to pursue a graduate degree. Perhaps the wisdom gained from five years of football explains his A to B running style: the quickest way to get somewhere is a straight line, even if there’s a linebacker in the way. Showing his age, he referred to Marshall as a “kid” in a big brother type of way after last week’s win. Skov usually takes the lead in the film room, asking more questions because he has seen more football.

Marshall is 18 years old, a freshman from Raleigh, N.C. whose big brother Keith plays running back for Georgia. Marcus Marshall is becoming more inquisitive in the film room, possibly because sometimes freshmen don’t have enough experience to know what questions they should ask. Marshall said playing running back is mostly instinctive, though there are a lot of details he’s trying to fine tune related to holding onto the ball (he had a fumble) and blocking. Though Marshall is becoming more confident in the film room, he will lean on Skov if he needs to know something.

“I learn a lot from him in there and out on the field,” Marshall said. “He’s real knowledgeable. He always asks good stuff and is a good guy to learn from.”

Skov was effusive in his praise of Marshall after the Alcorn State game.

“It’s good to see him really get out there and put some good stuff on film and really show what he can do,” he said. “He’s a talented kid, and I think he’s only going to keep getting better.”

Just because they are different doesn’t mean that Johnson will use them differently on Saturday against Tulane.

Instead, Johnson said he will sub by “feel.” Skov will remain the starter and Marshall will remain what he described as a good complement. Johnson said he won’t pre-determine how many plays either gets because it’s not something he’s ever done. The B-backs typically are subbed by possession, and not during possessions, so whoever starts a drive is likely to be the one to try to finish it.

There could be a third B-back in the mix this week: Marcus Allen, who isn’t as fast as Marshall or as strong between the tackles as Skov, so he’s the just-right back in a Goldilocks scheme.

Playing one, two or three may not make a difference this week because Tulane struggled to stop the run last week. The Green Wave gave up more 200 rushing yards in a 37-7 loss to Duke.

“I could envision games where three of them play, I could see two of them playing, I can see one of them playing,” Johnson said. “It’s just kind of the way it goes.”