Top-flight Hamilton Academical are out of the Scottish League Cup after losing to bottom-tier opposition for the second time this season.
The 2-1 defeat at Stranraer increases the pressure on manager Brian Rice, whose side prop up the Premiership and lost 8-0 to Rangers on Sunday.
St Mirren went top of Group G with a bonus point penalties win after being held 1-1 at home by Greenock Morton.
League Two Edinburgh City won 1-0 at Airdrieonians in Group H.
Hamilton, beaten 3-1 by Annan Athletic last month, were again in trouble away to a side three divisions below them when Thomas Orr gave Stranraer a half-time lead.
Hakeem Odoffin’s close-range header restored parity, but Darryl Duffy pounced in the final 10 minutes to give Stranraer victory.
Hamilton, who round off Group F against Albion Rovers on Saturday, can no longer qualify for the last 16, while Stranraer face Ayr United in a shootout for top spot.
In the Renfrewshire derby in Paisley, Jim Goodwin’s Premiership St Mirren were rewarded for first-half dominance when Jon Obika headed home.
But Morton came back strongly and substitute Ross MacIver equalised with his first touch, converting from close range on the hour.
St Mirren’s 6-5 win on penalties nudged them above Queen of the South on goal difference, with Morton and Partick Thistle two points adrift.
Blair Henderson’s fifth-minute strike was enough for Edinburgh City to see off Airdrie, with both sides out of contention to qualify.