Dundee United boss Jim Goodwin praised his side's "great resilience" as they recorded a third consecutive clean sheet to edge out St Johnstone in the Scottish Premiership and strengthen their bid for European football.
Defender Emmanuel Adegboyega profited from slack set-piece defending to tap in the first-half winner and move the hosts level on points with third-place Hibernian.
St Johnstone, who boosted their survival hopes last weekend with a shock win over Celtic, responded strongly in the second half but could not find an equaliser and remain five points behind Dundee at the foot of the table.
"Our defensive record this season has been really good and the last three weeks in particular, three back-to-back clean sheets," Goodwin told BBC Scotland.
"Of course we'd like to score more goals and make it a little bit more comfortable than what it has been but the group has shown great resilience.
"In the dying moments St Johnstone threw everything at it and we got some great blocks in."
The decisive moment came when a corner was played deep to the back post and Declan Gallagher knocked the ball back across for on-loan Norwich City defender Adegboyega to convert.
Although the hosts had control of the game, St Johnstone came close to an equaliser before half-time through Stephen Duke-McKenna and Victor Griffith.
The visitors had a real go in the second period and ended with five strikers on the pitch, but it was United who looked more likely to extend their lead.
Gallagher twice had free headers that he couldn't bury, while Louis Moult passed up a golden opportunity when one-on-one with Andy Fisher, who made a stunning block.
Substitute Josh McPake had two powerful drives deflected wide as Saints searched desperately for an equaliser, while Benjamin Kimpioka also fired wide.