Motherwell earned a 2-0 home win over Ross County on Sunday as the club locked up second place this weekend ahead of Inverness.
Inverness lost 2-1 to Dundee United on Saturday, which handed Motherwell second place, and the home side went out took care of Ross County with a pair of goals in the first half.
James McFadden tallied the opener in the eighth minute, and Chris Humphrey doubled the advantage just before halftime, with the home side easily seeing out the final 45 minutes.
Ross County remains in fifth place, three points back of St Johnstone.
The other contest on Sunday saw Hibernian claim a 2-1 comeback win at Hearts.
Darren Barr's goal late in the first half gave Hearts a 1-0 lead at the break, only for Leigh Griffiths to level the match early in the second half and Ross Caldwell to net the winning goal in the 90th minute.