Kris Commons' 79th-minute winner got below-par Celtic off to a successful start in the defence of their SPL title against Aberdeen at Parkhead as they picked up a 1-0 win.
The Pittodrie side looked comfortable enough as the champions struggled until Langfield made an horrendous mess of Commons' shot from distance at his near post after the Hoops midfielder had played a short corner with Joe Ledley.
Langfield, nicknamed Clangers, will not want to see his aberration again but Celtic will certainly have to do better in Finland on Wednesday night if they are to build on their 2-1 first-leg lead against HJK Helsinki in their Champions League third qualifying round tie.
Darren McGregor's stoppage time header salvaged a point for St Mirren from an entertaining 2-2 draw with Inverness at St Mirren Park.
Debutant Lewis Guy had given the hosts the lead just after the half hour mark with an accurate angled drive beyond Ryan Esson but two goals in the final 20 minutes from Nick Ross and Billy McKay had appeared to have handed the visitors all three points.
However, McGregor was in the right place at the right time to head home when Esson completely misjudged a cross from the right.
And in the aftermath of the goal Saints were reduced to 10 men as Guy was sent-off for clashing with Ross Draper in his attempt to get the ball out of the net.
Hearts secured a less-than-comfortable 2-0 win over Hearts secured a less-than-comfortable 2-0 win over St Johnstone at Tynecastle despite playing over half of the match against 10 men.
John Sutton's 30th minute penalty and a late David Templeton strike separated the two sides with Saints' striker Gregory Tade shown a red card for a scuffle in the box six minutes before half-time. at Tynecastle despite playing over half of the match against 10 men.
John Sutton's 30th minute penalty and a late David Templeton strike separated the two sides with Saints' striker Gregory Tade shown a red card for a scuffle in the box six minutes before half-time.
Ross County extended their unbeaten league run into the top flight as a goalless draw with Motherwell made it 35 games without defeat.
County produced a solid SPL debut and restricted Motherwell to very few chances at the revamped Global Energy Stadium in Dingwall.
Dundee enjoyed a respectable return to the SPL as they claimed a point after holding Kilmarnock to a goalless draw in their season opener.
Their route to the SPL may have been unusual and controversial in the eyes of some but Dundee demonstrated an ability to hold their own following a seven-year absence from the top division.