He strolled off the mound, paced around a bit then returned to the hill flexing his left leg.
The Pittsburgh infielders immediately surrounded the pitcher, and manager Clint Hurdle and trainer Ben Potenziano emerged from the dugout.
Rodriguez squatted down and flexed and extended the left leg for several minutes, and even tried a pair of pitches from the rubber. With the Chase Field crowd getting impatient with the delay, he finally relented and walked off the field.
The Pirates reported that Rodriguez will be treated Monday night and re-evaluated Tuesday.
Jeanmar Gomez came on in emergency relief of Rodriguez, who owned the Bucs' lone win of the season -- a 3-0 decision over the Cubs in the season's second game.
Tom Singer is a reporter for MLB.com and writes an MLBlog Change for a Nickel. He can also be found on Twitter @Tom_Singer. This story was not subject to the approval of Major League Baseball or its clubs.