Luke Hancock turned 24 a couple months back and has won NCAA tournament games at two different programs. Russ Smith is a few weeks from turning 23, and together they're the old men of a battle-tested Louisville team trying to repeat as national champions. Point guard Chris Jones was playing junior college ball at this time last year; he's the new guy, but he's 22 and almost four years past high school.

In the Kentucky backcourt, Aaron Harrison is the old man.

He's a minute older than his brother, Andrew. They're 19, a year removed from the high school all-star circuit.

The battle of Kentucky's Julius Randle and Louisville's Montrezl Harrell in the post in Friday night's Midwest Regional semifinal is a battle of grown men, regardless of age. In the backcourt, though, it's different.

Smith came back to school for one more run through this tournament. Kentucky wouldn't be here if it wasn't for the way the Harrisons have played lately.

Bring on their biggest challenge yet.

"All we have done all year is continue to get better," Kentucky coach John Calipari said. "We hit some pots, like every team, you hit a hole that you don't play well. But they believed in themselves.

"Andrew will know what I'm saying, I did not do a great job with him early in this year. I didn't, and I'm the first to admit it. I told him, 'Make me look good.' That's what I said to him."

Calipari was going to put the ball in the hands of his freshmen guards because they were his best guards. With an all-freshman starting lineup, there were going to be bumps.

And there were. Now, with Kentucky having dispatched unbeaten Wichita State to set up this game with Louisville, Calipari looks good.

So do the Harrison Twins.

"It's not really a different season, but I think we're a different team now," Aaron Harrison said. "And we're just playing together as a team, and we're just having more fun."

Aaron Harrison has scored in double figures in six straight games. He played 39 minutes against Wichita State, scoring 19 points. Andrew Harrison almost had to miss the Wichita State game due to an elbow injury.

He led Kentucky with 20 points and also had 3 assists. On Thursday, he said the elbow "is still sore, but better. In a game like that (against Wichita State), so exciting, you just don't feel it. It stops."

The challenges at this time of year don't. If they're not immune to the big crowds and the pressure that comes with donning the Kentucky jersey, they're certainly more used to it now.

"As (Aaron) played better, guess what? Andrew played better," Calipari said. "On (our) team, guys are accepting roles. Individuals are losing themselves into the team."

Said Andrew: "I think I've come pretty far and our team has come pretty far. We have great chemistry. Everyone as individuals is getting better. The team is getting better."