Dahlin was widely expected to come off the board with the first selection, and the Twitter reaction was instantaneous when his name was called:
The 18-year-old blueliner made some waves in the Swedish Hockey League for Frolunda HC during the 2016-17 season, but he broke out in 2017-18.
Playing against much older and more experienced competition, Dahlin registered seven goals and 13 assists for 20 points to go along with a plus-4 rating in 41 games.
Also, in six playoff games, Dahlin put up one goal and two assists.
Dahlin was the youngest player at the 2017 World Junior Hockey Championships before taking on a major role for Sweden in the 2018 World Juniors.
The Swedes won the silver medal in the tournament, and Dahlin was named the top defenseman at the event after racking up six assists in seven games.
Dahlin was already viewed as the top prospect in the 2018 NHL draft class at that point, and his performance in Buffalo, New York, only served to bolster his status.
During the lead up to the draft, Dahlin was often compared to a fellow Swedish defenseman in former Detroit Red Wings star Nicklas Lidstrom.
Lidstrom is a Hall of Famer and is often mentioned in the discussion of the best all-around defensemen to ever play the game.
In March, Lidstrom paid Dahlin a huge compliment by saying the youngster is better than he was at the same age, per Helene St. James of the Detroit Free Press.
Red Wings scout Hakan Andersson backed that up in April by telling St. James, "He's good at everything. He has great size, he is a great skater, he has very good hands. He's extremely smart, and he has very high dedication. There is a lot to like."
Due to his well-rounded game, Dahlin is perhaps the only player in the draft who is viewed as a slam dunk in terms of being a perennial NHL All-Star.
The Sabres are a long-suffering franchise, as they haven't reached the playoffs since 2010-11.
Despite that, they have some quality young talent on the roster with center Jack Eichel leading the way in that regard.
Defense has been an issue, though, as they ranked 29th in the NHL in goals allowed last season. Aside from Finnish defenseman Rasmus Ristolainen, Buffalo's blue line leaves plenty to be desired.
Drafting Dahlin gives the Sabres another potential stud on defense, and perhaps its second superstar along with Eichel.
The young Swede is only the second defenseman to go No. 1 overall in the past 12 drafts, and the first since the Florida Panthers took Aaron Ekblad with the top pick in 2014.
Denis Potvin is the only defenseman to be taken No. 1 overall before enjoying an elite-level career, but every indication is that Dahlin is an elite prospect capable of bucking that trend.