DEFENSIVE mistakes have blighted Argyle all season, and it will lead to them being relegated unless they cut them out.

Argyle scored three goals for the second successive away game at Bramall Lane on Saturday.

But, unlike at Barnsley a fortnight earlier, when they won 3-1, they ended up being beaten by Sheffield United.

Or should that be beaten by themselves?

Argyle trailed 3-0 after 48 minutes, and all three goals were preventable with better defending.

That said, you had to admire the way the Pilgrims battled back from a seemingly hopeless position.

First, they cut the deficit to 3-2, with goals from half-time substitutes Yannick Bolasie and Joe Mason.

Then, after a goalkeeping blunder from David Stockdale gifted the Blades a fourth goal, they still refused to surrender.

Striker Jamie Mackie, who was tenacious all afternoon, scored a splendid goal in the 87th minute.

And Mason came so close to putting the Pilgrims on level terms in stoppage time.

In the end, though, Argyle paid the price for some abysmal defending as they crashed to their 19th defeat in the Championship this season.

Here is how the drama unfolded at Bramall Lane:

7 MINS: Argyle conceded their 5,000th goal in the Football League when striker Henri Camara gave United an early lead.

All it took was one pass from midfielder Mark Yeates to open up the Pilgrims.

Reda Johnson could not cut the ball out, close to the halfway line, and Camara sprinted clear.

Kari Arnason could not catch him as Camara moved into the penalty area.

He then sent a low, angled shot into the corner of the net, past the despairing dive of Stockdale.

35 MINS: United midfielder Jamie Ward was a constant threat to Argyle in the first half and was rewarded for his endeavours as he made it 2-0 with a fine finish.

Blades' left-back Toni Kallio took a throw-in quickly and the Pilgrims were caught cold.

Yeates, who was shadowed by Argyle winger Craig Noone, touched the ball back to Kallio.

There was then no-one near Kallio as he fired a shot into the penalty area.

Neither Arnason nor Camara could make contact, but the ball reached Ward, who fired it high into the net from almost on the penalty spot.

48 MINS: Argyle head coach Paul Mariner made the bold, and what proved to be shrewd, decision to send on Bolasie and Mason at the start of the second half.

However, it seemed a lost cause for the visitors when more sloppy defending led to United taking a 3-0 lead.

Blades' right-back Nyron Nosworthy hurled a long throw-in to the near post and Argyle's Chris Barker was shoved over by United captain Chris Morgan.

Even so, there was still no excuse for Ward being all alone inside the six-yard area.

He controlled the ball neatly before blasting it past Stockdale from close range.

Stockdale should have perhaps tried to catch the long throw-in, or at least punched it away, as it was so close to his line.

50 MINS: Argyle were thrown a lifeline after United 'keeper Mark Bunn made a mistake.

Bunn tried to punch clear a long throw-in from Arnason, but could not get near to the ball because of a crowd of bodies.

Instead, it flicked off the top of the head of on-loan Arsenal centre-back Kyle Bartley.

It dropped to Bolasie, who had the simple task of slotting into an empty net from six yards out.

58 MINS: Mason and Arnason both went close for Argyle before they eventually grabbed their second goal.

Midfielder Luke Summerfield, on as a substitute for injured defender Reda Johnson, headed the ball into the path of Mason.

The 18-year-old cleverly found some space inside the 18-yard area and he coolly steered the ball low past Bunn.

82 MINS: Disaster struck for Stockdale, and Argyle, as the visitors prepared to launch a late onslaught in search of an equaliser.

Stockdale dived on top of the ball as striker Richard Cresswell latched onto a pass from Ward.

Then, having got up and bounced the ball once, he threw it onto the ground, without realising Cresswell was still behind him.

Cresswell sprinted past a startled Stockdale and rolled the ball into the empty net.

It was a dreadful mistake, and one Stockdale should not have made, but he will know that and must now try to bounce back from it.

It does, however, raise the question whether Romain Larrieu could return to the team against Preston North End at Home Park this Saturday.

87 MINS: Stockdale saved from Cresswell and Yeates before Mackie gave Argyle renewed hope.

Mason flicked the ball inside to him, aided by a deflection off Morgan, and Mackie swivelled and shot low into the corner of the net.

It was Mackie's seventh goal of the season and, undoubtedly, one of the best.

90 +3 MINS: United tried to shut up shop, sending on defender Jordan Stewart for Cresswell in stoppage time.

But, despite this, Argyle almost drew level at 4-4 in a tense finale.

Barker launched the ball towards Mackie, but Morgan came over the top of him and diverted it into the path of Mason.

Without any second thought, Mason strode up and unleashed a fierce 20-yard shot.

It was sweetly struck, but the ball went inches past the outside of the left post, with Bunn beaten.

The travelling supporters applauded Argyle off the pitch after the final whistle, and deservedly so.

It had been a stirring comeback, with youngsters Bolasie, Mason and Summerfield all contributing hugely after coming off the bench.

But the damage had been done in the first 48 minutes of the match.

Argyle will probably need to win at least six of their last 14 league games to stay in the Championship.

There is no chance of them achieving that target unless they tighten up defensively.