CHICAGO -- Following the highly anticipated Major League debut of Brailyn Marquez in September, fellow Cubs pitcher Adbert Alzolay wanted to ease any concerns over the prospect's rough performance.

"Just to let you guys know," Alzolay said on a Zoom call, "we have a good one in him. He's going to be great. And he's going to be so good for this team in the future."

That future might arrive for Marquez in 2021.

The Cubs will be giving Alzolay an opportunity to seize a rotation job this year, and younger arms like Cory Abbott, Marquez and some others are not far behind. Marquez, in particular, is one of the more highly touted pitching prospects the Cubs have had in years, and he currently ranks as the organization's top prospect per MLB Pipeline.

On Sept. 27 last year, the Cubs gave Marquez his first taste of the Majors after the left-hander spent the season training at the team's alternate site in South Bend, Ind. There were flashes of the potential, but the lefty also looked raw and wild -- no doubt dealing with debut nerves -- and in need of more development.

"I couldn't believe it when I was invited to take that step that we all dream of," Marquez told MLB.com in Spanish at MLB's Rookie Program. "I felt really happy to be next to a lot of professionals, to spend time with them, learn from them. I know it wasn't my best debut, but I learned a lot of things that I didn’t learn when I was in the Minors."

Marquez threw 33 pitches to seven batters. The big lefty flashed an overpowering fastball, while mixing in a breaking ball and changeups. He walked three, fired a pair of wild pitches and was charged with five runs on two hits. Marquez did register one strikeout -- against White Sox slugger (and the 2020 American League MVP) José Abreu.

"I'm sure there was a lot of emotion," Cubs manager David Ross said after the win. "It's hard to judge somebody off their first appearance in the big leagues. He got a punchout. I was happy for that. It took him a minute to settle in."

Marquez -- who will turn 22 years old on Jan. 30 -- fired a 99.6 mph fastball to Edwin Encarnación at one point. Per Statcast, that was the fastest pitch by any Cubs pitcher during the 2020 campaign. His 99.4 mph strikeout pitch to Abreu ranked second. In fact, Marquez and Craig Kimbrel are the only names among the 13 fastest pitchers for Chicago last season.

Marquez's focus in 2020 was initially to work on his physical shape, and then improve his mechanics. From there, the lefty worked on enhancing his changeup and curve, while working on a sinker. There were cries among the Cubs faithful to summon him to the big leagues, but the team prioritized progress over the promotion.

"Day by day, I used my time to work hard and get the best out of myself," Marquez said, "so that in 2021, I can try to give the best of myself when Spring Training starts. It's what I’ve been doing since my first year: work hard, not put in my mind, 'I can't', but, 'Yes, I can do it', and that way I can keep moving forward."

In his last Minor League season in '19, Marquez went 9-5 with a 3.13 ERA and 128 strikeouts against 50 walks in 103 2/3 innings between Class A South Bend and Class A Advanced Myrtle Beach. He made five starts in the upper Class A level, posting a 1.71 ERA with 26 strikeouts and seven walks in 26 1/3 innings.

MLB Pipeline recently unveiled its 2021 ranking of the best lefty pitching prospects in baseball and Marquez checked in at No. 8 overall. He was No. 63 in Pipeline's Top 100 Prospects for 2020, and his spot in that list for '21 will be revealed on Jan. 29.

At the Rookie Program, Marquez was asked what his main goal is for the season ahead, which could include joining the Cubs again on the big league stage.

"The truth is, I'd like to win a World Series, with me there, fighting for it," Marquez said. "The team that gives me the opportunity to help win a World Series ... that would be marvelous for me."