Haaland scored twice as City thrashed Sparta Prague 5-0 in the Champions League on Wednesday, his first spectacular gravity-defying effort in which he sent the ball into the net from shoulder height.
His double took his tally for the season to 13 and his total return in the competition to a remarkable 44 from 42 games.
Foden, who scored City’s first goal in a routine win, said: “I don’t know how he did it. He’s a freak, isn’t he?
“I’ve seen him score against Dortmund as well, he showed he can score goals like that. He is different.
“I’d probably pull my groin if I tried it myself!”
Foden headed City to their second win of the league stage after three minutes, but it wasn’t until Haaland’s breathtaking effort just before the hour that the result looked certain.
It was the first of three goals in a scintillating nine-minute spell that saw John Stones score another header before Haaland finished off a slick move for his second.
Mateus Nunes then capped off a fine individual performance with a late penalty after the Portuguese himself had been fouled.
It was a record 26th consecutive game without defeat for City in the Champions League, breaking rivals Manchester United’s previous best of 25 sets – although they lost the tie on penalties in that run.
Foden said: “We’re going well, we’re in a good period. We’re in the top half of the league so we’re happy with that.
“It was difficult after the first goal, but much better in the second half. Scoring a lot of goals is always a good feeling, so we’re happy.”
It was a pleasing performance for Foden, who was player of the year last season but has had a slow start to the current campaign, partly due to fitness issues.
He said: “I still have steps to go. I need a series of games to be at my best, but as long as I continue to progress and my fitness also recovers, and if I continue to score as well – that’s the most important thing – I’m taking steps in the right direction.”
Nunes was also pleased with his performance, which included two assists as well as his goal.
The Portuguese said: “I feel I have settled into the best this season. I’m calmer, I don’t stress so much. I just have to keep working like this.”
Nunes was also in awe of Haaland’s wonder shot.
He said, “How did you do it? I thought so. It was crazy. I don’t know how he got his foot on the ball as high as he did. It was a top goal.”