A second-half collapse condemned the below-par Rocks to a third home defeat of the season - and left them wondering where their next goal is coming from.
Two classy finishes by Simeon Akinola and a simple header by Michael Peacock wrapped it up with a bit to spare for Harrow, and the Rocks now find themselves in their worst run of home form for more than two years.
The Rocks were sharply out of the blocks and robbed Harrow of possession straight from kick-off, leading to a sweeping move that ended with Harvey Whyte’s inswinging cross from the left being gathered by keeper Elvijs Putnins.
Another attack down the left led to a nice ball into the six-yard box from James Crane but Putnins got to it before Carl Walshe could pounce at the near post.
Steve Harper was in for his first start since a hamstring injury and was involved in an exchange of passes with Mu Maan just outside the box that the latter couldn’t quite turn into a shot on goal.
Whyte was causing Harrow some headaches down the left and was constantly finding team-mates with an impressive range of passing.
Jon Marzetti ran on to a ball down the right and his cross looked perfect for Whyte on the penalty spot but the chance eluded him.
The first Harrow chance was ballooned over the bar by Akinola after a loose ball broke to him 20 yards when Bob Wollerston looked clear on goal only to be denied by a timely Matt Partridge tackle.
The Rocks - playing with Whyte and Harper supplying the width to centre-forward Walshe and with Maan in a fairly deep midfield role - were having most of the play but Harrow were coming into it and Akinola was close to connecting with a ball across the face of goal.
Maan’s run down the inside right channel ended with him being crowded out as he prepared to shoot.
Midway through the first half Harper’s cross fell to Whyte at the far post but he fluffed his shot.
Whyte looked the Rocks’ most dangerous player going forward and he almost worked himself space for a shot in the D on 28 minutes - moments before Crane was played in but shot too close to Putnins.
Maan was frustrated by a lack of options after he bustled into the box and ended up shooting high and wide from an impossible angle.
It was almost all Rocks and Harper was next to chance his arm, firing in a low 12-yarder that Putnins got down to hold at the second attempt at his near post.
Crane threw himself at a Harper cross on 35 minutes but clashed heads with his marker and play was stopped.
Three minutes before the break a foul on Whyte just outside the angle of the box gave the Rocks a free-kick in a lovely position but Harper curled it straight to the grateful keeper.
The hosts were almost punished when Borough broke and allowed a cross to bounce to Wollerston, who shot narrowly wide of Craig Stoner’s post.
The Rocks emerged for the second half wondering how they could improve on a record of having scored only one home league goal all season.
And it wasn’t long before they were left needing two goals for victory as Akinola put Harrow ahead. There looked nothing on for him as he was faced by two defenders on the corner of the penalty box but he made a bit of space for himself and curled a perfect shot beyond Stoner and into the top corner.
The crowd of 357 - a decent figure for a murky midweek night - had fallen a bit silent as the Rocks went in search of some inspiration in the final third.
They’d obviously been told to get the ball into the box at every opportunity but when Marzetti tried to do that with a high ball from right-back, it sailed straight into Putnin’s arms.
Akinola had his eye and fancied another spectacular when he took a free-kick 25 yards out on 62 minutes, but it was high and wide.
Ashley Robinson replaced Whyte as the management tried to conjure up a much-needed killer instinct in front of goal.
That was followed by a Harrow sub - Michael Barima coming on for Darelle Russell. Maan was replaced by Lewis Stockford for the Rocks at the same time.
But Stockford had no sooner entered the fray than the Rocks were two down as Peacock headed in Garry Jones free-kick from just inside the left touchline.
Now it was a long way back from the Rocks as they faced up to their third home defeat of the season.
But they might have got back into it a minute later as a corner fell to centre-half Matt Partridge six yards out. He caught it on the half-volley but skied it.
Marzetti bustled forward for a chance but skewed his shot and it didn’t trouble Putnins.
Harrow continued to threaten on the break before the Rocks made their final change by bringing on Ollie Pearce for Walshe, who had struggled to impose himself on the game.
Crane headed wide from a Partridge cross as time began to run out on the Rocks.
And if time hadn’t run out, luck had when Akinola burst into the box to fire low past Stoner to wrap up the points for Borough with ten minutes left.
Tuck was named man of the match on a night when there weren’t too many contenders.
To their credit, the Rocks kept on plugging away - but it was more hit and hope than anything when they did get the ball forward.
They should have got one back when Marzetti crossed for the unmarked Stockford but he scuffed his shot and it didn’t worry the keeper.
Robinson had at least livened up the home team’s forward play and one long-range piledriver wasn’t too far wide.
Rocks: Stoner, Marzetti, Wollers, Crane, John, Partridge, Harper, Walshe, Maan, Whyte, Tuck. Subs: Robinson, Cody, Pearce, Stockford, Boyle.
Harrow: Putnins, Williams, Jones, Yala, Peacock, Leech, Ehvi, Wollerston, Akinola, Russell, Lawal. Subs: Burrell, Barima, Tararov, Delgado, Fehmi-Gil.
Ref: A Laver (Portsmouth)
The Rocks are at home again on Saturday when Bridgwater Town visit in the FA Trophy - when they will hope one or two of their senior players will be fit to get the season back on track.
Get all the latest from Nyewood Lane in the Observer on Thursday.