It did it the hard way, coming back from 2-0 down to beat Western 4-2 at Memorial Park on Saturday.
Mosgiel started brightly, with good attempts from Riley Anderton and Alex Cox.
Western's first opportunity came on 13 minutes, when Levi Waddington was forced into a fine save.
Western went ahead on the 16-minute mark, when Ryan Stanley found himself unmarked in the box and slid in to score.
With Western starting to press, Mosgiel was forced into conceding a free kick and Alex Cox was booked as a result.
Mosgiel started to rally but the game swung again and Western scored through Brennan Potts in the 34th minute.
Mosgiel heads did not drop and it pulled one back four minutes later, when an Anderton corner was not dealt with by James Hinton and Deeley slotted home.
Two minutes later, Anderton beat his marker on the right wing and cut the ball back for Lewis Wall to score the equaliser.
In the 43rd minute Ben Deeley was fouled in the penalty box and referee Lindsay Robinson had no hesitation in pointing to the spot.
Alex Cox stepped up and calmly slotted home to give Mosgiel a 3-2 lead five minutes after being 2-0 down.
Deeley nearly put Mosgiel further ahead minutes later as he beat two players, but shot just wide.
The second half started like the first as both teams created early chances.
As the half wore on, both had periods of possession and it went end to end.
But it was not until late in the game that Mosgiel made it safe.
Cam Anderson scored with two minutes to play, making it 4-2 following a great pass from Alex Cox.
A dramatic game still had time for more drama, when Alex Cox was shown a red card in the 93rd minute.
Caversham continued Dunedin's resurgence with a 3-2 victory in Christchurch against Nomads United, at Tullett Park yesterday.
Connor Neil scored from the penalty spot on 17 minutes after Ben Kiore was taken out.
Kiore then supplied the pass that allowed Campbell Thompson to double the lead.
Nomads pulled one back, before Ryan Fleming made the game safe to Caversham scoring with 10 minutes to go.
Nomads scored in injury time to leave Richard Murray's team with a few nervy moments.
The result secures Caversham a top four finish.
Otago University was thrashed 5-1 by Nelson Suburbs in Nelson, while Cashmere Technical also claimed a 5-1 win over Coastal Spirit.
Nelson holds a one-point lead over Cashmere heading into the final round.
Coastal is three points back from Cashmere and Caversham is a further two behind.
Mosgiel is in a tie for fifth with Nomads and Western, on six points.
- Neville Watson & Chris Pike
