Sometimes the most beautiful moments can occur in the ugliest of situations. Midway through the second half of this critical relegation contest, the game seemed to be descending into an unattractive, goalless war of attrition. Then Darren Ambrose intervened.

With the ball at his feet, 25 yards from goal, the Crystal Palace midfielder chipped it up with his left foot and volleyed it impeccably beyond the previously impassable Steve Simonsen.

It was enough to win a match in which both teams were desperate for the points. The two clubs, relatively recent fallen giants from the Premier League, are precariously close to dropping into League One, but this victory has enabled Palace to move five points clear of third‑bottom Sheffield United.

The Blades were one of the pre-season promotion favourites. That seems a long time ago. They are now winless in 10 matches under Micky Adams. "I'll get plenty of attention but I'm not worried about me, I'm worried about the team," the manager said. "But you can't legislate for a wonder goal."

Palace had shown some early boldness, as Ambrose and James Vaughan drove in long-range efforts that went off-target. United retained their composure though and had a chance of their own following Stephen Quinn's corner, as Richard Cresswell had a close-range effort blocked.

The home side quickly regained the initiative, displaying increasing confidence with their passing and movement. Kagisho Dikgacoi, the midfielder who shone for South Africa in the World Cup, was making his debut. His 15th-minute strike was parried by Simonsen before Ambrose directed the rebound wide. Energetic Ambrose then came close with a well‑struck, swerving, 30-yard free-kick that Simonsen diverted with agility.

United used the flanks well, though. As half-time approached, they had two clear chances after accurately delivered, curling crosses from the right. The first came from Daniel Bogdanovic, a scorer for United in their previous two games, both 1-1 draws. He supplied Quinn, whose eight-yard shot was pushed away by Julián Speroni. Next it was Bjorn Helge Riise's turn, as his cleverly flighted ball gave Palace a fright but Patrick McCarthy headed clear for a corner.

Both teams continued to play relatively openly, albeit scrappily, as the second half began. Riise again displayed his qualities with another swirling cross from the right that Speroni had to smother as Cresswell dived in, looking to apply the touch that would have taken the ball beyond the Palace goalkeeper.

But, as the half wore on, the game became a more tetchy and disjointed affair, with the referee feeling compelled to make three bookings during a messy 10-minute spell. It certainly did not seem likely to produce the moment of brilliance that was about to follow. Perhaps less surprising was that it was Ambrose provided the much-needed injection of class. "It was a bit of magic, a great goal," said the Palace manager, Dougie Freedman. "Darren has had a few injuries this year but he's been dedicated and I told him it wouldn't be long until he would be scoring goals again."

That goal freed Palace and, instead of retreating into protective mode, they created the better late chances, as James Vaughan's shot was blocked by Shane Lowry before Ambrose shot over the bar late on. Marcus Bent did almost pinch a point at the death but Nathaniel Clyne cleared the danger on the line.

With United losing ground on Palace, the last thing they need is another high-pressure game. Sadly for them, they face a trip to second-bottom Scunthorpe on Tuesday night. Lose that and the seemingly unthinkable – United dropping into the lower divisions – will suddenly seem an uncomfortably realistic prospect.