Observations from the Buffalo Bills' 20-16 preseason win over the Minnesota Vikings on Friday night:

Kolb gets his chance, plays full half: In his first action of the preseason, Kevin Kolb played the entire first half, finishing 13-of-21 passing for 111 yards and an interception. The Bills always have said they would give both Kolb and rookie EJ Manuel a fair shot at the starting job, and tonight might have been Kolb's best chance to prove himself. The results weren't overly positive, although Kolb led the Bills offense on two scoring drives late in the first half, looking more comfortable than he did in the early stages of the game.

Manuel again solid, but not spectacular: Manuel entered the game at the start of the second half and led the Bills on an 80-yard touchdown drive, completing all six of his passes for 44 yards. More importantly, Manuel did not throw an interception for a second consecutive game. However, the Bills (or Manuel) opted not to take any shots downfield, something they are expected to incorporate into their offense this season. Instead, many of Manuel's throws were in the short range, but he did complete a 27-yard pass to rookie receiver Brandon Kaufman in the third quarter. Manuel also had the benefit of playing against the Vikings' second-team defense.

Penalties becoming a major issue: The Bills were flagged 14 times for 106 yards in the contest, one week after being penalized nine times against the Indianapolis Colts. The flags have to be a growing concern for head coach Doug Marrone, especially considering nine of them came in the first half, when many of his starters were still in the game. Among the flags was a key holding call in the red zone against Colin Brown, who made his second consecutive start at left guard. In what remains an open battle, that won't help his case.

Defense generating pressure: The Bills' defense kept the pressure on Vikings quarterbacks throughout the game, finishing with four sacks for 38 yards. Outside linebacker Jerry Hughes had two sacks, including a sack and forced fumble of Matt Cassel in the second quarter.

Hogan, young receivers making strides: First-year receiver Chris Hogan continued to stand out for the Bills, playing nearly the entire game. Hogan was the team's leading receiver with four catches for 34 yards and was targeted a team-high seven times. Meanwhile, Kaufman and Marcus Easley continue to be second-half standouts, with five catches for 91 yards between them. Undrafted rookie Da'Rick Rogers had a quiet night, being targeted twice and making one catch for six yards. On special teams, second-round pick Robert Woods returned a punt 34 yards, one week after third-round pick Marquise Goodwin had two long kickoff returns.

Mario sits out: Defensive end Mario Williams (foot) dressed but was announced as an inactive for the game. He played in two series in the preseason opener, and the Bills continue to manage the health this preseason of their highest-paid player.

What's next: The Bills return to St. John Fisher College for their final four practices of training camp, beginning Sunday. They travel to face the Washington Redskins in the third preseason game next Saturday.