South Shields endured an afternoon of frustration as they were unable to make their chances count in a 1-0 defeat at Southport.
The Mariners dominated much of the proceedings at The Big Help Stadium and went close on a number of occasions, but fell to a loss after a second half penalty was converted by the hosts.
Shields named an unchanged team as they aimed to make it three consecutive wins, following back-to-back 1-0 home victories over Tamworth and Buxton.
They were bright in possession from the first whistle, although chances were difficult to come by in the early stages.
Marcus Carver had the game's first attempt at goal, but his curler from the left of the area was comfortably held by Myles Boney.
The Mariners began to exert themselves more as the first half progressed and there were almost openings for Paul Blackett and Lirak Hasani after impressive build-up play.
CJ Clarke was proving a constant threat on the right and he almost scored a tremendous goal after coming inside and hitting a stunning strike with his left foot which home goalkeeper Chris Renshaw sent over with his fingertips.
Jordy Mongoy also had a sight of goal after good interplay with Jed Abbey, but he screwed his shot wide.
Southport almost caught Shields out at the other end when David Morgan's corner picked out Jack Bainbridge in space. Boney held the midfielder's header.
Hasani and Blackett were combining well and went close to opening the door for the Mariners on 39 minutes. Hasani clipped a pass over the top and Blackett beat Renshaw, only for his flicked effort to land on the roof of the net.
Shields went closer still when Clarke's cross was deftly nodded inches past the post by Mongoy.
It was an ultimately frustrating half for the Mariners, who had no goals to show for their efforts despite largely dominating proceedings.
Shields went agonisingly close to opening the scoring just over a minute into the second half. Blackett motored into the area and after appearing to be knocked off-balance, his shot was cleared as far as Lirak Hasani, whose sweet strike was somehow cleared off the line.
They were hit with a sucker punch in the 50th minute when Southport were awarded a contentious penalty following a challenge on Brad Holmes. Declan Evans stepped up to dispatch the spot-kick into the bottom corner.
The Mariners responded well and almost immediately threatened an equaliser, with Mongoy bringing the ball inside from the left before firing over.
Shields went closer as Blackett raced in down the right and pulled a ball across goal which Hasani could not quite get to, and a further chance saw Abbey's shot cleared off the line.
There was more frustration when Abbey's superb ball from the right was almost converted by Blackett, who just could not stretch enough to get on the end of it.
Boney was alert at the other end to turn away an effort from Holmes before the game entered something of a lull as Shields were unable to convert possession into opportunities.
They did find an opening on 75 minutes after some patient probing, but Mongoy's effort was brilliantly saved at the near post by Renshaw.
Blair Adams was the next to go close, with his prodded effort from 10 yards deflected narrowly wide.
There would ultimately be no way through for the Mariners as Southport saw out their victory.
Shields will aim to bounce back on Tuesday when they travel to Spennymoor Town in Vanarama National League North.
South Shields: Boney, Clarke, Adams (c), Liddle, Broadbent, Smith, Hasani (Martin 75), Abbey, Heaney (James 57), Blackett, Mongoy. Subs not used: Lufudu, Morse, Briggs.
Attendance: 1,165 (169 away).
Image: Kev Wilson.