INDIANAPOLIS — The Indianapolis Colts fell to 2-2 on the season Sunday with their 31-24 loss to the Oakland Raiders in their 2019 Week 4 matchup at Lucas Oil Stadium.

The Colts saw the Raiders (2-2) jump out to a quick 14-0 lead not even halfway through the first quarter, and couldn't keep up from there. Not helping matters were several uncharacteristic mistakes during the first two quarters — penalties, dropped passes, missed assignments, etc. — that made Indy's valiant second-half comeback attempt for naught, and the Colts' seven-game home winning streak is officially snapped.

"Tough loss here at home," head coach Frank Reich said. "We had a little momentum going into this game; really were looking forward to carrying that momentum, and we did not do that."

Here are the FIVE THINGS LEARNED from Sunday's loss to the Raiders:

» ROUGH START: The Colts came into Sunday's game one of the better-disciplined teams in the NFL, but would commit four crucial first-half penalties, unofficially drop five passes and allow the Raiders — who were coming off two straight blowout losses — to run wild for 110 yards in the first two quarters. By halftime, Indy was trailing 21-10, and it could've been a lot worse than that if not for a couple mistakes on the Raiders' end, too. "It's hard to explain," Reich said. "I mean, that has not been indicative of our offense. We've had very few drops, very few penalties, and today it was hard to swallow. And I don't know what it is — we've been doing a good job at that; we just have to fight to eliminate those."

» MAKING IT INTERESTING: As sloppy as the first half was, the Colts at least made things interesting over the final two quarters, twice getting to within a touchdown and extra point in the last six minutes of the game. In the second half, Indy outgained the Raiders 202-160 and committed just one penalty, and a four-yard touchdown pass from Jacoby Brissett to Chester Rogers with 5:27 left got the Colts to within seven at 24-17. But after a stop from the Indianapolis defense, Raiders safety Erik Harris would pick off a Brissett pass on the Colts' next offensive drive, running it 30 yards into the end zone for the touchdown, basically putting the game out of reach, 31-17, with 2:09 left. Tight end Eric Ebron would escape for a 48-yard touchdown reception with 1:10 to go to once again get Indy to within seven, 31-24, at the 1:10 mark, but Oakland would close it out from there. Nevertheless, Brissett liked the fight he saw in his team. "We have a tough team," Brissett said. "Like I said, they're cheering after the pick-six and we still come back with another opportunity to score, and hope that we can get a stop on defense — whatever happens, we still have a chance to go tie the game up. So, I mean, we've got a resilient group. We've got a lot of good players."

» SHEARD'S BACK: A minor knee procedure during training camp was responsible for sidelining Colts starting defensive end Jabaal Sheard for the first three games of the season, but after increasingly working his way back to practice over the last two weeks, No. 93 was back Sunday against the Raiders, albeit on somewhat of a pitch count. But Sheard — one of the top run-stopping defensive linemen in the league — certainly didn't look like he had much rust to knock off, as he finished with four tackles and was a constant presence in the Oakland backfield. "It felt good to be back out there with the team, with my brothers again," Sheard told reporters after the game. "You miss the game, you miss competing, but overall it felt good to be back out there."

» GET WELL SOON: One of the major storylines for the Colts entering Sunday's game was injury-related, as top wide receiver T.Y. Hilton (quad) and free safety Malik Hooker (knee) were each dealing with their respective ailments. Parris Campbell, Zach Pascal, Chester Rogers and Deon Cain combined for 12 receptions for 145 yards in Hilton's absence; Campbell, meanwhile, looked to be the primary deep option for Indy on Sunday, but quarterback Jacoby Brissett wasn't able to connect with the rookie wide receiver on three different attempts down the field. "I honestly wouldn't have thrown the ball if I didn't feel like the chemistry was there," Brissett said. "The way it worked out, we just didn't catch it. The good thing is that teams see that and going forward they have to respect that. I'm sure me and him will connect on those further throughout the year. So, (I) don't lose faith in that." Hooker, who will be out a few weeks, according to Reich, was replaced in the lineup by rookie Khari Willis, who had a strong outing with nine tackles (one for a loss) and a pass defensed on a near-pick on a play late in the second quarter. In other Colts-related injury news, running back Marlon Mack was listed with an ankle injury and sat out the entire fourth quarter. We'll see if Reich has an update on Mack later today when he has his weekly conference call with reporters.

» NOTES OF INTEREST:

— The Colts' offense converted all three fourth down attempts, which was the most for the team in a game since Dec. 10, 2017 at Buffalo (3-of-4). Dating back to 1950, it was the only the ninth time Indianapolis converted three-or-more fourth down attempts in a game.

— Kicker Adam Vinatieri, who had six points on the day (one field goal and three extra points) tied Rohn Stark and Jeff Saturday (197) for the fifth-most games played in Colts history.

— See more stats and notes from Sunday's game by clicking here.