The Warriors could still feasibly finish first as the regular season comes down to an exciting finale next weekend - but will be looking over their shoulders as Munster lie one point behind.
A bonus-point win against Zebre would ensure a semi-final at Scotstoun but, if the form books are anything to go by, the Italians will be confident of ending their own season on a high.
Wins against Edinburgh and Ospreys - finishing off the Welsh region's playoff hopes - in their last two games has lifted Zebre off the bottom of the table at the expense of Italian rivals Treviso.
And with a spot in the European Rugby Champions Cup on the line, Townsend believes Zebre will be just as motivated as the Warriors come Saturday.
"In their last two games Zebre have beaten both Edinburgh and Ospreys and that underlines the threat they will bring with them on Saturday," Townsend told the Glasgow Evening Times.
"They are playing with confidence and they are scoring freely and they will be determined to finish above Treviso and try to claim a European place for next season.
"We will have to make sure we are every bit as professional as we were at Treviso. That was one of the best performances of our season and we must maintain these standards."
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