FOXBOROUGH, Mass. -- Unheralded rookie free agent Gunner Olszewski was told he didn't make the New England Patriots' initial 53-man roster on Saturday, only to be called back later in the day with the surprising news that he had earned a spot.

"It was a roller coaster. That's the best way to describe it," Olszewski said Sunday after his first practice as a member of the defending Super Bowl champions. "For one second you think, 'I don't know what's going on.' The next second, 'I'm a Patriot.' At the end of the day, it doesn't really matter how it happened. What happened is I'm a Patriot now. I'm just proud to be here, and proud to go to work."

Olszewski's rise is similar to how the Patriots signed cornerback Malcolm Butler as an undrafted free agent in 2014 -- long after the 90-man roster was already set. The club signed Olszewski on May 23, as it needed depth at receiver because of injuries. Olszewski was a defensive back at Division II Bemidji State (Minnesota), but the Patriots switched him to receiver in their rookie minicamp as a tryout player.

Olszewski, who is generously listed at 6 feet and 190 pounds, played in four preseason games and finished with five catches for 69 yards. He added nine punt returns for 118 yards, including four fair catches, as well as four kickoff returns for 95 yards.

He is now among the team's options to handle those return duties in the season opener Sept. 8 against the Pittsburgh Steelers.

"Gunner's a tough kid. He's improved a lot. He's shown some versatility," coach Bill Belichick said Sunday. "I still think he has a long way to go, but if he continues to work hard and is able to continue this rate of improvement, I think he has enough talent to be a productive player for us."

Olszewski said the initial phone call from the Patriots was naturally disappointing, but he was optimistic that the team wanted to keep him around on the practice squad. He was watching college football with fellow rookie Jake Bailey when he received the second phone call, which he referred to as "the best call of my life."

"Those five hours felt like about 24," said Olszewski, a native of Alvin, Texas, who was the Northern Sun Intercollegiate Conference Defensive Player of the Year in 2018. "It ended on a high note, so it was all worth it."

Now that he has a job with the Patriots, Olszewski said his mindset is simple.

"I'm hoping to keep that job," he said.