Ralf Rangnick says Manchester United cannot afford to rely solely on Cristiano Ronaldo despite his match-winning hat-trick against Norwich City.
Ronaldo hit the 50th treble of his club career against the Canaries, guiding United into a 2-0 lead before sealing the victory with a free-kick after the visitors had fought back to level the contest.
The legendary forward has hit 15 goals in 26 Premier League appearances this season, accounting for 28.8 per cent of the Red Devils' goals during a frustrating campaign.
Despite Ronaldo's treble moving United to within three points of fourth-placed Tottenham after both they and north London rivals Arsenal suffered surprise defeats, Rangnick was frustrated by his team's continued reliance on the 37-year-old.
The interim manager also expressed his annoyance at United's defensive display after Keiran Dowell and Teemu Pukki's strikes threatened a stunning turnaround at Old Trafford.
"It was the second time now [that Ronaldo hit a match-winning treble] like against Spurs with the same result, 3-2 like today," Rangnick told BBC Sport.
"But we should not only rely on him.
"In general, offensively at times we played pretty well at times today, although in the first half sometimes we slowed the game down and didn't make use of the overlap situations on the wings, so even there we could have made more out of it.
"In general, in possession today was okay, a pretty good game, but defensively I was not happy at all."
Ronaldo has now hit 20 or more goals in all competitions in each of his past 16 club seasons, a run which began in 2006-07 during his previous spell at Old Trafford.
Meanwhile, his set-piece winner represented the 58th direct free-kick goal of his career, and means only David Beckham (18) and James Ward-Prowse (13) have more such goals in the Premier League.
United's quest for Champions League qualification sees them face tough-looking fixtures against Liverpool and Arsenal during the coming week, and Rangnick asserted that his side would not get away with another poor defensive performance against a higher quality of opponent.
"After we scored the second goal, it should have made life easier for us," he added. "But it didn't, we lost our structure, we weren't aggressive enough.
"Even before they scored their first goal, they had two or three transitional moments where they outnumbered us, which should not happen if you are 2-0 up.
"This is also a question of being clever, of being smart in moments like this. All of a sudden, it was 2-2 and David de Gea kept us in the game with a brilliant save, and with that brilliant free-kick from Cristiano we managed to get the three points.
"But we have to raise our game against the ball in the next three games."