Rennie was far from thrilled despite the win and said they needed to work on their lineout.
"I just didn't think we built enough pressure today to really put them under the screws, we are a pretty fit side and we need to use that to our advantage, and maintaining a bit of pill would certainly help," he said.
"Our lineout didn't get going which meant we played a lot of the game without the ball, so a positive is we got to do a lot of defending today. And considering the amount of ball we played without, to restrict them to two tries was a pretty good effort."
The match kicked off at the unusual time of 4pm to help the players adjust to the warmer climates they can expect in South Africa and Argentina this season. However, it didn't do a lot for crowd numbers, withmany people still at work when play began.
The Tahs, who started Wallabies stars Michael Hooper and Kurtley Beale as well as former All Black Zac Guildford, scored first through halfback Nick Phipps.
New Chiefs signing and league convert Glen Fisiiahi restored parity on 18 minutes when he scored a sensational try. He made a lovely break down the right then got the ball back a few passes later to finish off the play he started.
Halfback Tawera Kerr-Barlow was next to cross for the Chiefs, but Waratahs winger Reece Robinson, formerly a Parramatta Eels player in the NRL, tied the game up after running 50m to score near the posts. The teams went into the sheds 12-all at halftime.
As the minutes ticked by the game turned rather messy, with a plethora of stoppages and substitutions.
Neither side really looked like scoring the winning try until Foketi made a break in the final seconds to put Ioane over to score.
New Chiefs signing, flanker Mitchell Karpik, had to be helped from the field with a knee injury early in the second half while Maama Vaipulu (shoulder) will also undergo scans.
- Chiefs 17 (Glen Fisiiahi, Tawera Kerr-Barlow, Monty Ioane tries; Charlie Ngatai con) Waratahs 12 (Nick Phipps, Reece Robinson tries; Kurtley Beale con). HT: 12-all.
