The Boston Celtics have appeared to flip the switch in these playoffs, as they swept the Indiana Pacers in the first round and routed the Milwaukee Bucks on the road in Game 1 of their second-round Eastern Conference series on Sunday afternoon.

So, why the sudden change?

Celtics big man Al Horford credits Kyrie Irving and Gordon Hayward for changing the team's mindset, per Jay King of The Athletic:

“As a group we’re much more confident because of those guys,” said Horford, who finished with 20 points, 10 rebounds and three blocks in Boston's Game 1 victory.

As for how Irving feels about that? He says he is just being himself:

“I’m just going out there and just being me,” said Irving, according to Adam Himmelsbach of The Boston Globe. “That’s what I’m best at doing, playing very aggressive, managing emotions, trying to give what the game needs.”

Irving totaled 26 points and a playoff career-high 11 assists on Sunday.

The C's were the preseason favorite to win the Eastern Conference, with many pegging them as a 60-win team going into the year. However, the Celtics had a whole lot of struggles throughout the regular season and finished with just 49 wins, well below people's expectations.

However, based on Boston's talent, there were some who felt the C's still had a deep playoff run in them. With Hayward seeming to get more comfortable as the year progressed, Boston began to look much more dangerous in April.

Now, the Celtics will have a chance to put a stranglehold on their series against Milwaukee in Game 2 on Tuesday night.