Ea Lla Koto lost 2-0 to the Absa Premiership leaders at James Motlatsi Stadium, as Willard Katsande slotted an early penalty before fellow Zimbabwean Mitchell Katsvairo added a second strike in the 69th minute in Orkney.
Sithole told SuperSport: "I think we lost concentration. Early in the game with the penalty and with the second we lost our markers. When you do that in your defensive third, you concede. That's where we went wrong.
"The team played very well. They did exactly what we wanted them to do.
"We lacked a little bit in the final third. We have to create more chances. We seemed to get a bit tired in the last 20 minutes. We needed more width. We have to work on that, but I'm happy with the performance."
Meanwhile, Sithole confirmed he was set to relinquish the reins at Stars amid talk Giovanni Solinas is returning to the club.
Sithole also oversaw a goalless draw with SuperSport United after Frenchman Denis Lavagne was fired just three games into the season.
Solinas led the Bethlehem-based outfit last term before resigning in the off-season.