When the Indianapolis Colts selected Andrew Luck with the number one pick in last week's NFL Draft, it was no doubt a proud moment for Stanford. His presence helped catapult the Cardinal from an afterthought in the Pac-12 to a national powerhouse, and after leading the team to back-to-back BCS Bowl berths and tossing 82 touchdowns in his illustrious career, he was more than worthy of being Stanford's first top overall pick since John Elway nearly 30 years ago.

However, with the Andrew Luck chapter officially closed, Stanford's second-year head coach David Shaw now has the unenviable task of replacing the once-in-a- generation type signal caller.

Stanford began spring workouts with five quarterbacks in competition for the starting job: Brett Nottingham, Josh Nunes, Robbie Picazo, Evan Crower and Kevin Hogan.

When the Cardinal hit the field for their annual Cardinal & White intra-squad spring game however, it became clear that it has become a two-horse race between the junior Nottingham and the senior Nunes.

Of course, playing behind Luck throughout their careers thus far, neither owns much game experience. Nunes completed just 1-of-2 passes for seven yards in 2010, and did not even attempt a pass in the 2011 season. Nottingham served as the primary backup in 2011, seeing action in six games while going 5-of-8 for 78 yards and a touchdown.

Despite Nottingham having the upper-hand on the depth chart last season, it was Nunes who saw the majority of the reps in the spring game. He looked effective at times, throwing for 167 yards and two touchdowns, including an impressive 45-yard score to Ty Montgomery hauled in between two defenders. With the positive moments came plenty of negative as well, as he connected on just 11- of-29 passes and also tossed an untimely interception.

"I felt like I left a lot of plays on the field today," said Nunes of the spring game. "We've got some of the best defensive linemen and outside linebackers in the country, so they definitely gave us a run for our money."

While Nunes received the bulk of the playing time and found the end zone twice, Nottingham arguably had a better afternoon, completing one more pass than Nunes (12) on 10 fewer attempts (19), finishing with 118 yards.

Despite his impressive performance, Nottingham is fully aware that he is in the midst of a tight competition, knowing full well that the momentum could swing at any moment.

"I still have a lot of stuff I can clean up," Nottingham said of his performance. "I feel the offense, especially the wide receivers, stepped up and made some really nice plays today. It was tough for our offense to get into a rhythm today."

Even though it's still early in the process of selecting his future starter, Coach Shaw found plenty to like about his quarterbacks' play, but also acknowledged that there is a lot of room for improvement.

"I felt our top two quarterbacks (Nottingham and Nunes) played pretty well at times," said Shaw. "Josh made some really nice throws that were dropped and missed a couple of checks and reads we can't miss."

"Nottingham made some good throws, but once again, the same thing," he continued. "There are some things you can't see from the stands, but he missed some things as well."

Shaw and the rest of the coaching staff know that they cannot replace Luck, who finished his career as Stanford's all-time leader in touchdown passes (82), completion percentage (.687), passing efficiency (162.76) and total offense (10,387 yards). Achieving numbers anywhere near as good as Luck's would be nearly impossible and unfair to expect.

Filling Luck's shoes will be even more difficult considering the other players Stanford lost to the professional ranks last week. One of last year's most trusted targets, tight end Coby Fleener (34 receptions, 667 yards, 10 touchdowns), will be joining Luck in Indianapolis after being selected with the second pick in the second round.

The Cardinal also said goodbye to their most trusted offensive lineman in David DeCastro, who was taken by the Pittsburgh Steelers in the first round with the 24th overall pick.

Though no one should expect Heisman-caliber numbers from either Nunes or Nottingham, that doesn't mean the Cardinal can't continue to be successful. The offense does retain one of the best running backs in the conference in Stepfan Taylor, who carried the ball 242 times for 1,363 yards and 10 touchdowns in 2011, while also adding 25 receptions for 182 yards and two scores.

Shaw will continue to lean heavily on Taylor this fall. The Cardinal had a specific style of offense with Luck at the helm, and that isn't expected to change with a new leader.

"Just like when Andrew was here, we still need to run the ball effectively," said Shaw. "Our play action has to be effective. Our tight ends have to perform and of course we have to defend. Then it's up to our coaches to find the right matchups."

"We might not go through the first half up 28 points on a team," he continued, "but we have a great scheme that tries to utilize the talents of each person. It's going to be exciting to see how we morph and change to utilize the talents we have."

Shaw insists that the competition between Nunes and Nottingham remains a dead- heat and will continue throughout the spring and summer until one candidate emerges as the go-to guy come the 2012 season opener against San Jose State. The incumbent will never live up to his predecessor, but the right choice will be crucial if Stanford has any hope in continuing its success in the Pac-12.