The San Francisco 49ers and Indianapolis Colts will kick off their Week 5 contest on Sunday at 10:00 a.m. PT/1:00 p.m. ET from Lucas Oil Stadium. While the Niner Faithful will be keeping an eye on key 49ers players like Carlos Hyde and DeForest Buckner, there are a number of Colts players who could be big factors in the matchup.

We reached out to our friends over at Colts Wire and spoke with site editor Kevin Hickey (@KevinHickey11), who was kind enough to share his three key Colts players to keep an eye on during Sunday's game. Below are those three players.

Of course, you can read all of Hickey's coverage of the Colts at Colts Wire.

Jacoby Brissett

The first player named by Hickey is an obvious, yet important, one. Jacoby Brissett has been filling in for Andrew Luck over the past three games after taking over for Week 1 starter, Scott Tolzien. The Colts traded for Brissett, who was the third-string quarterback for the New England Patriots, on September 2.

While Luck returned to practice this week in a limited fashion, he has been ruled out for Sunday's game. He is making his way back from surgery in January to repair a partially torn labrum in his throwing shoulder and had not practiced with his teammates since the final week of the 2016 season. Luck missed all of the Colts' minicamps, organized team activities, training camp, and every preseason and regular season practice since.

Through Brissett's three-straight starts, he has completed 53 of his 90 passes for 632 yards, two touchdowns, and two interceptions. He also had two rushing touchdowns in a 31-28 Week 3 victory over the Cleveland Browns.

"The offense will almost always hinge on the play of the quarterback and with Brissett, he can elevate the unit if he is efficient," Hickey told 49ers Webzone. "He's proven to have strong first halves but has struggled to put together complete games. Officially a month of being in this offense, it will be intriguing to see if he makes any progression."

49ers defensive coordinator Robert Saleh is not overlooking the "underrated" Colts quarterback.

"He's not as much of a run threat as Russell [Wilson] or Cam [Newton] but I think Brissett is a really underrated quarterback," Saleh said on Thursday. "The guy can make every throw. He sits back there tall, strong. He does have good patience and he can throw everything. Against Seattle, he made a couple of throws that were pretty impressive so he's a pretty good quarterback back there. He's only been there what? About a month now since they traded for him? A month and a half? Like everyone else, as he gets comfortable, he's only going to get better."

Ryan Kelly

Second-year center Ryan Kelly will make his season debut on Sunday against the 49ers. He missed the first four games of the season after suffering a foot injury on August 10 during a joint training camp practice with the Detroit Lions. Kelly's return could not have come at a better time for the Colts. Deyshawn Bond, who had been filling in during Kelly's absence, was placed on injured reserve this week after he tore his quad during Sunday's loss to the Seattle Seahawks.

"The Colts first-round pick in 2016 had a superb rookie season but he's missed the first four games this year due to a foot injury he suffered in training camp," said Hickey. "Making his debut Sunday, Kelly will be a huge factor in anchoring the offensive line."

Indianapolis made Kelly the 18th-overall selection in the 2016 NFL Draft. During his rookie year, he started all 16 games at center for the Colts. While the offensive line as a whole gave up 44 sacks in 2016 (fifth-most in the NFL), Kelly gave up none.

Jabaal Sheard

On March 10, the Colts signed linebacker Jabaal Sheard to a three-year deal worth up to $25.5 million. Sheard spent the previous two seasons with the New England Patriots and the four before that with the Cleveland Browns, who selected him in the second round of the 2011 NFL Draft.

Sheard, who is the starting right outside linebacker for Indianapolis, has 12 total tackles and a sack this season. His 17 quarterback pressures rank 14th among edge defenders but lead the Colts.

"The first-year Colt has done well thus far, leading the team in pressures," said Hickey. "The Colts pass rush has improved but they will need to keep taking steps forward if it is going to make a difference. That starts with Sheard applying pressure."

Sheard also ranks fifth in the league against the run, according to Pro Football Focus.

"Like [49ers defensive lineman DeForest] Buckner, Sheard has been a pocket-wrecking force off the edge," wrote our own Peter Panacy while identifying Sunday's top 5 player matchups. "PFF currently grades him at 85.6 -- No. 12 out of 95 qualifying edge defenders."