"There's always a big sledgehammer waiting around the corner, I reckon. You just never know," Fagan said after the Lions demolished a depleted Port Adelaide at the Gabba, 19.12 (126) to 9.13 (67).
"Don't take form for granted. We were in a bit of trouble at six [wins] and six [losses], and we've been able to win our last seven games, which is pretty exciting.
"There's still four games to go, some challenging opponents to play ... every week's a final now, everyone's jockeying for the best position, so we really only have our mind on next week."
The Lions had to work hard to shake off the Power, who hung in until midway through the third quarter before the home side exploded, kicking 14 goals to 5 in a crushing second half.
The result leaves Fagan's men fourth on the ladder, a game clear of Adelaide with four rounds to play, with matches against Carlton, Hawthorn, the Gold Coast and Collingwood to come.
On form, however, the Lions should fear none of them.
While the Power worked hard early to close space and force the Lions to use the ball more by hand instead of with their usual precise kicking game, the Lions had too much class and too many avenues to goal.
Port Adelaide coach Josh Carr said his team was unable to go with the home side as they dialled up the pressure.
"In the second half, you could see their intent right from the start, the way they shifted the footy, and we were really slow to squeeze the ground and they cut through us," he said. "Quality teams like that make you pay."
The Lions kicked seven majors to three in the third quarter, highlighted by Sam Draper, who plucked a centre-square ruck contest and galloped to 60 metres before landing a decisive blow.
Will Ashcroft was superb with two goals from 30 possessions, while Zac Bailey was destructive with three majors from his 26 and Harris Andrews was typically impassable in defence with 13 marks.
Perhaps the most encouraging sign for Brisbane was the inside game of Hugh McCluggage, who had his best match for the year, finishing with 29 possessions, five clearances and a goal as an inside midfielder.
Brisbane's forwards also fired, with Logan Morris, Kai Lohmann and Charlie Cameron kicking three goals apiece.
Jason Horne-Francis was a shining light for Port, keeping them in the contest with a superb kicking exhibition that resulted in nine score involvements and three direct assists.
But without Port's usual centre-square assassin Zak Butters, Horne-Francis lacked midfield support, and the Power did well to stay with the Lions for as long as they did.
Port Adelaide were also let down by their set-shot kicking, with spearhead Mitch Georgiades ending with 2.4.
Georgiades was also involved in a third-quarter incident with Ty Gallop, with the Lions defender certain to come under the scrutiny of the match review panel.
Fagan said Lions forward Oscar Allen, who played in the reserves on his return from injury, had done all he could in his push to regain a senior berth.
But it won't be easy for the former West Coast captain, with Fagan admitting it was hard to change a winning formula with a forward line that was already scoring heavily.
"It's a little hard to get in, but it's good to have players in the reserves who can step up if we need them," he said.
Fagan said defender Bruce Reville, who has missed the last two matches for personal reasons after the birth of his second child, was also a possibility to break back into the side.
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