Motherwell consolidated their third-top place in the Scottish Premier League with a convincing win over a lacklustre St Johnstone.
Saints had started the brighter until a disputed 17th-minute penalty was dispatched by Michael Higdon.
Nicky Law added the second from close range three minutes later.
Jamie Murphy volleyed in seven minutes after the break, Liam Craig pulled one back with a 59th-minute penalty before Henrik Ojamaa's late breakaway double.
It means Motherwell stretch their lead over Dundee United to five points as they chase a place in next season's Champions League qualifiers.
The Perth side's plans were disrupted just before kick-off, with the influential Dave Mackay picking up an injury.
It meant a start for Steven Anderson in defence for a Perth side already without their lethal SAS partnership up front, with Francisco Sandaza suspended and Cillian Sheridan a surprise omission.
Marcus Haber was handed a lone striking role, with Craig and Jody Morris returning from suspension, while Jamie Adams dropped to the bench.
However, despite a drive from Murphy that curled just wide from 20 yards, St Johnstone edged the opening exchanges and Darren Randolph saved decent long-range efforts from David Robertson and Derek Riordan.
The match turned when Anderson was adjudged to have brought down Humphrey just inside the box.
Well's flying winger had evaded Craig's attempt to haul him down and Anderson slipped as he went to into his challenge.
Referee Bobby Madden decided that what looked like an accidental challenge had sufficiently impeded Humphrey and Higdon sent Alan Mannus the wrong way from the penalty spot.
Humphrey pounced on some hesitation from Morris three minutes later before delivering a ball across the face of goal for Law to slide home from close range.
Riordan curled a free-kick just wide moments later, but Saints were struggling to cope with Motherwell's attacks and Humphrey in particular.
The right winger drew an excellent one-handed save from Mannus, who held Murphy's follow-up.
Murphy then found space down the left before cutting inside to pass to Higdon, whose flicked effort on the stretch from 18 yards was touched just wide by Mannus.
Randolph saved another long-range Riordan strike and then came off his line quickly to block from David Robertson to maintain Motherwell's lead going into the break.
Murphy was making the most of being handed a start with Keith Lasley, who had returned from suspension, in place of Omar Daley and Stuart Carswell.
The forward superbly volleyed home a fine Tom Hateley cross after the break and perhaps should have done better than fire against the chest of goalkeeper Mannus minutes later.
Saints were handed a lifeline when Shaun Hutchinson hauled back Haber and Craig powered the resulting penalty past Darren Randolph.
The visitors were given new lease of life, but Well survived the pressure and, when Humphrey again broke clear, substitute Ojamaa slotted in with seven minutes remaining.
There was still time for another Ojamaa strike on the break to creep under Mannus and just over the line.