Collins put the Town ahead from the penalty spot in the 25th minute after Accrington goalkeeper Dimitar Evtimov was sent off for a second yellow card, before Mpanzu sealed the victory with two goals after the break - the second an absolute cracker - as he turned in a man-of-the-match performance.
Harford was forced to make four changes to his starting line-up, with Marek Stech in for his first start since August replacing James Shea, who was ill overnight, and captain Alan Sheehan coming into the defence as a replacement for the suspended Andrew Shinnie.
James Collins returned from serving his one-match ban along with fellow forward Kazenga LuaLua, with George Moncur and Harry Cornick dropping to the bench.
The Town were presented with the perfect opportunity to take the lead in the third minute when Collins pounced on a poor touch from Stanley keeper Dimitar Evtimov as he looked to control a Mark Hughes backpass. Collins was brought down by the home stopper, who was shown a yellow card by referee Carl Boyeson, but then redeemed himslf by saving the league's top scorer's penalty.
Evtimov denied Collins again on 14 minutes when he sent a header straight at the keeper, after Bradley had headed Sheehan's first corner back across goal, then Accrington gave a reminder of the threat they carried, Jordan Clark cutting in from the right
The breakthrough did come after 25 minutes, and it was from the penalty spot. Evtimov came racing off his line as LuaLua's pace saw him reach a ball over the top first. The keeper collided with him, Boyeson pointed to the spot and then showed the Bulgarian his second yellow card.
Stanley boss John Coleman brought Jonny Maxted on for midfielder Scott Brown, and the sub keeper's first job was to pick the ball out of the back of the net as Collins this time took the opportunity for his 23rd goal of the season.
The Town striker survived a penalty appeal at the other end as he appeared to push Billy Kee in the back, then Sean McConville fired over the bar from just outside the area.
On 33 minutes, Maxted pulled off a terrific double save from Stacey after quick free-kick by Berry put the Town right-back in on the right side of the area.
LuaLua then missed a great chance to make it two in the 39th minute, when his initial shot was blocked on the edge of the box by Hughes, who was then robbed of possession by the Town forward, who fired wide with just Maxted to beat.
Stacey had the first Town chance of the second half, bursting through a couple of challenges on the right and firing in a low shot that Maxted did well to turn away at his near post. Lee was next to have a go, cutting in from the left, before LuaLua fired similarly straight at Maxted from just outside the box.
Three golden opportunities came within seconds on 55 minutes, after Lee had been fouled 20 yards out. Moncur - just on for the injured Sheehan - curled his free-kick around the wall but Hughes retreated to the goal-line and blocked the shot, with Maxted beaten.
Collins was onto the loose ball, volleying it towards goal, but Hughes blocked again, straight into the path of Lee, whose header was brilliantly clawed away by Maxted.
The Accrington sub keeper was in the right place at the right time again just after the hour when LuaLua unleashed a bullet from the left side of the area, pushing the ball behind for a Town corner.
The Hatters were dominating possession, and a patient build-up from the centre-halves in the 66th minute eventually saw the ball worked up to Moncur 25 yards out, but his right-footed curler flew high into the 1,319 travelling Town fans behind the goal.
The second goal finally came in the 68th minute and it was Mpanzu who collected a nod down from Pearson, after a right-wing corner from Justin, ten yards out and swivelled to place it past Maxted and a host of defenders on the line.
Harry Cornick was introduced for Lee, who had picked up a knock, in the 72nd minute and the former Bournemouth man should have put the result beyond doubt in the 80th minute when Moncur crossed low from the left, but Maxted once more pulled off a fantastic save with his left leg before Ross Sykes cleared his follow-up off the line.
Mpanzu then put the gloss on a wonderful performance three minutes from time, when he picked up the ball on the left corner of the box and bent an absolute beauty around Maxted for his second of the game and fifth of the season.
Back to Kenilworth Road now for AFC Wimbledon on Tuesday night, when the Town could seal promotion if results on Monday go our way.
TOWN: Stech, Stacey, Pearson, Bradley, Sheehan (c) (Moncur 52), Mpanzu, Berry, Justin, Lee (Cornick 72), Collins, LuaLua (Baptiste 84). Subs: Cummings, Read, Panter, Isted
Yellows: Berry
Goals: Collins (pen) 25, Mpanzu 68, 87
STANLEY: Evtimov, Johnson, Hughes, Donacien, Clark, Brown (Maxted 25), McConville, Sykes, Barlaser, Conneely (c), Kee (Armstrong 63). Subs: Maxted, Richards-Everton, Nolan, Zanzala, Sousa, Smyth.
Yellows: Evtimov
Red: Evtimov
REFEREE: Carl Boyeson
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