Lasogga joined Leeds on a season-long loan from Bundesliga side Hamburg on deadline day and wasted no time in announcing himself to the Elland Road faithful.
The 25-year-old had not started a game since last November after falling out of favour at his parent club but he was handed the number nine shirt vacated by Chris Wood in a clear sign he is Leeds' new main man.
"He's a very good striker and he proved that today in his first appearance," said Christiansen.
"He scored two nice goals but he also combined well and held the ball up which is very important.
"It was a good game, not only from him but also the rest of the players.
"As a striker you need the confidence to prove your skills and today was a good start for him.
"He started the game after only a few days with the team and his performance and two goals will help him a lot to get that confidence."
Lasogga has a baby due imminently and Christiansen joked that he would do all he could to ensure his new recruit would be available for the visit of Birmingham.
"I have to have a direct line with his wife to tell her not to have it until Tuesday night," added Christiansen.
Lasogga set Leeds on their way against Burton and the hosts were out of sight courtesy of Kalvin Phillips' curling effort and Pablo Hernandez's penalty on the stroke of half-time.
Kemar Roofe got in on the act just after the restart and Lasogga nodded home his second as Leeds continued their unbeaten start to the season in emphatic fashion.
"It was a good team performance, the result was good, the scoreline was good and the fans were amazing," said Christiansen.
"But it's just three points, you can't take any more.
"The attitude and the behaviour of the players was massive but now we need to focus on Birmingham."
It was a torrid afternoon for Burton and boss Nigel Clough admitted they will have to do it the hard way if they are to take their Championship stay into a third season.
"We weren't very good and they were excellent from start to finish," said Clough.
"We couldn't do too much about the quality of the goals they scored. It's very rare you get a goalkeeper that's conceded five goals and can't say he had a chance with any of them.
"It's the nature of Burton Albion in the Championship. We know we're going to lose games.
"It's not nice when you lose 5-0 but you have to hold your hands up sometimes and say the opposition were excellent."
The Brewers dealt a huge blow to Leeds' play-off hopes in April but Clough believes they are a stronger outfit this term.
"Leeds' movement and the quality of their finishing was top-class," he added.
"If they play like that, they're genuine promotion contenders."