Much was riding on the match for both sides, with Slough having the opportunity to extend their lead further due to Bedworth's game at Barton being called off earlier in the day. Sixth-placed Uxbridge, meanwhile, were looking to build on a recent win over Fleet and their midweek comeback against Burnham which saw them rescue a point.
However, the game failed to live up to its billing, and was a rather patchy affair played on a difficult pitch.
In the end, Slough achieved their twelfth clean sheet of the season, and if Slough are to maintain their challenge for the league title, much will depend on the ability of James Warrington and the players in front of him to continue to keep the opposition at bay.
Sonner sent an early header over the bar from a Steve Sinclair cross, the winger getting a lot of space down the right hand side in the opening stages.
The Slough midfield was working hard to create opportunities, but the final pass often let them down. But with 26 minutes played, Slough were awarded a penalty thanks to a clumsy shove by defender Rob Fitzgerald on Dan Burnell, who was trying to control a Paul Coyne cross. Referee Leach pointed to the spot without hesitation, allowing Burnell himself to send Liam Stone the wrong way from the penalty spot.
Minutes later, Sonner went close but could only sidefoot an Adam Martin cross just wide after the midfielder had worked hard to evade his marker on the left.
Despite it being a fairly even and closely-contested first half, Uxbridge threatened only sporadically, with James Warrington dealing uncomfortably with one cross, and easily saving a fiercely-struck free kick from the league's top scorer Michael Murray.
Neither side really made an impression in the second half, though Leon Yarnie proved more of a menace, having a penalty appeal waved away and a shot blocked.
Slough, though, proved why their defensive record has been so impressive this season with another determined display, and after the home side doubled their lead on 63 minutes, the result felt like something of a formality. A long pass forward from Warrington put Burnell through on goal after Fitzgerald had failed to cut it out. Whilst the defender did well to get back and attempt to atone for his mistake by blocking Burnell's shot, Sean Sonner was on hand to sidefoot past Stone and into the bottom corner from 15 yards.
Murray went close with a well-hit free-kick which had Warrington diving across to his right, but the ball flew past the post. Leon Yarnie then had a half-chance after wriggling through a crowd of players, but he pulled his shot well wide.
Sonner clipped the top of the bar with a header and Paul Coyne volleyed wide late on, but the three points were secured.
Uxbridge Line up
Liam Stone, Gavin Brown, Howard Hall, Rob Fitzgerald, Mark Dennison, Stuart Farrell, Danny Julienne, David Lawrence, Michael Murry, Leon Yarnie, Craige Tomkins. Subs: Wayne Carter, James Duncan, Max Howell, Hussien Warsame, John Peacock