Esmael Goncalves scored twice as St Mirren booked their place in the quarter-finals of the William Hill Scottish Cup.
The 21-year-old striker, on loan from Portuguese side Rio Ave, took his tally to four goals in three games as the Saints recorded their third victory in six days.
Goncalves headed home to break the deadlock six minutes after half-time and doubled the hosts' advantage eight minutes later.
"It's been a great week, we are starting to find that level of consistency that we were striving for," Lennon said.
"I am delighted at the effort of the team and that they are finally getting the rewards for those efforts.
"Esmael was fantastic again and he's only going to get better. He's had quite a baptism at the club and he's going to have a fantastic career."