In the four-week NFL preseason, the third game is considered the most important. Starters play little — if at all — in the final game because of injury concerns. Coaches expect to see progress in the key test before the regular season.

The Washington Redskins showed some progress Saturday afternoon in a 30-17 victory over the Indianapolis Colts at FedEx Field.

For Redskins fans, the main story line was the first meeting of rookie quarterbacks Andrew Luck and Robert Griffin III — the Nos. 1 and 2 selections in the 2012 draft — during a game in which the teams’ starters played into the third quarter. Fans are eager to watch their careers unfold while awaiting the results: Did the Colts get the better player in Luck or will Griffin become a bigger star for the Redskins? The matchup also intrigued Redskins coaches, who sought immediate answers about Griffin’s development and the effectiveness of a defense playing without injured starters Brian Orakpo and Brandon Meriweather.

Despite his inexperience, the polished Luck, who ran a pro-style offense at Stanford, presented exactly the type of late preseason challenge that defensive coordinator Jim Haslett wanted. Smart and deceptively quick, Luck impressed in his first two preseason games and he burned the Redskins for a long touchdown pass on a perfect throw. From a pass rush and containment standpoint, though, Haslett obviously had the Redskins well prepared.

After the first-team offense’s poor showing last week against the Chicago Bears, Coach Mike Shanahan and his son, Kyle, the team’s offensive coordinator, wanted to see better timing. That starts with Griffin, who took a step forward against the Colts by making quicker decisions. Griffin still locked on receivers too long at times and needs to improve his accuracy on deep throws.

But he was steadier overall and didn’t take unnecessary chances with his body. He was in better rhythm passing and running. Based on what the Shanahans wanted Griffin to do, it was a net gain for them.

Then there was running back Alfred Morris, who ran even harder and with better results than he produced in his encouraging first start against the Bears. He also made a strong stand in pass protection, which wasn’t the case last week.

Morris is doing everything the coaching staff told him he would have to do to make a move up the depth chart. As coaches are fond of saying: The film doesn’t lie.

With the Redskins set to close the preseason in only a few days (they face the Tampa Bay Buccaneers on Wednesday at FedEx), Shanahan does not plan to have starters play in the last game. The good thing for Shanahan is, he already has seen what needs from the Redskins. Let’s look, too.

Strong signs from Griffin

The Shanahans never expected Griffin to become a finished product in one preseason. They know that would have been an unrealistic goal for him.

When the Shanahans analyze the first two quarters against the Colts, they’ll see that Griffin was in a better grove this week. Griffin’s timing, especially in cycling through his reads in the passing game, was much improved.

Griffin didn’t have big stats. He only completed 11 of 17 passes for 74 yards. Again, though, his performance in the preseason isn’t about stats; it’s about progress.

Griffin had a nice moment on his four-yard touchdown pass to Santana Moss late in the second. He did a good job corralling a high snap to his left, rolled right and made a perfect pass to Moss just inside end zone line near the sideline.

Several of Griffin’s passes, particularly while he was on the move, were not accurate in his last game. On Saturday, Griffin overthrew Pierre Garcon on a deep pass to start the game. He also missed Garcon on another long ball that he should have thrown toward Garcon’s left shoulder instead of his right one. Sill, there’s a lot there for the Shanahans to build on this season.

Defense holds up

The Redskins had reason to be worried when Orakpo (shoulder) and Meriweather (knee) left the 33-31 loss to the Bears because of injuries. Orakpo is a Pro Bowler and one of the team’s defensive leaders. Meriweather essentially locked up the starting strong safety job with his work in the offseason and training camp.

Although the Redskins and the players said the injuries are not serious, Shanahan took no chances: Orakpo and Meriweather won’t play again until the season opener against the New Orleans Saints.

With Orakpo and Jackson out Saturday, that opened opportunities for backups. Rob Jackson filled in well for Orakpo and Tanard Jackson, playing for Meriweather, showed why he could move into the starting lineup soon.

Coaches really like Rob Jackson because of his pass-rushing ability, which he displayed often in the first half while harassing Luck. One of Jackson’s best plays occurred on the Colts’ opening possession in the first quarter.

With the Colts facing second and 25 from the Indianapolis 17-yard line, Jackson split a double team and applied significant pressure on Luck, whose pass fell incomplete in the middle of the field. On third down, Jackson maintained his leverage in a pile and stopped running back Donald Brown for a three-yard gain, which prompted the Colts to punt.

Now this next sentence may seem crazy, but hang with us to explain: The Redskins don’t lose a whole lot if Jackson replaces Orakpo occasionally. Orakpo is much more athletic than Jackson, a converted hand-down defensive end. That’s a fact. Jackson, however, is a fundamentally sound pass rusher, coaches say. He understands the importance of the use of hand placement and body weight and leverage in engaging blockers and winning battles. He made an impact against the Colts and has in other spot duty, too.

Meriweather and free safety Madieu Williams are the starters in the Redskins’ reconfigured secondary.

Jackson, though, was a first-teamer with Tampa Bay and figures to be part of the rotation.

In the first quarter Saturday, he delivered a big hit on wideout T.Y. Hilton to break up a pass. He dropped in coverage and made the right read, coming up quickly to jar the ball loose from Hilton when he and Luck seemed to have teamed on a short gain. Coaches revel in that type of instinctive play.

Luck combined with Hilton for a 31-yard touchdown pass in the second quarter, beating Williams in the left corner of the end zone. But Luck rarely had time to relax in the pocket. In addition to Jackson, nose tackle Barry Cofield and end Stephen Bowen, among the starters, were also strong in the pass rush.

Another rookie impresses

Morris ran for 107 yards (with a 7.6-yard average) and scored his first touchdown. His best number? Zero.

That’s how many times Morris failed to pick up blitzes. Against the Bears, he missed his assignment on a play that led to the Bears recovering a Griffin fumble.

Morris continued to make one cut and hit the hole with great acceleration. He dragged would-be tacklers for extra yards and always seemed to fall forward for a few more yards.

He’s not a breakaway runner. That’s not his game. But on several solid runs in the first half — Morris’s best was for 24 yards — he showed more than enough of a burst.

Veteran Tim Hightower played Saturday for the first time since tearing his anterior cruciate ligament last October. Second-year backs Roy Helu and Evan Royster are both struggling with injuries. Shanahan has started rookie running backs before. Just saying.

For Jason Reid’s previous columns, go to