(Image source: Minneapolis Star Tribune)

BY: JOSH FRYDMAN

Even the Doc can’t beat the heat.

Phillies Ace Roy “Doc” Halladay left Monday's Phils-Cubs game at Wrigley Field in the fifth inning because of a heat-related illness.

MLB.com's Todd Zolecki says game time temperature in Chicago was 91 degrees, with a heat index approaching 105.

"It was startling to see Halladay struggle like this. His mental and physical preparations are second to none. But this heat was rare.”

The heat snapped Halladay's streak of 63 straight starts of six or more innings pitched on the road. That’s the longest streak in the majors in nearly 100 years.

But even the best can’t always escape the heat. Here’s what an emergency physician tells CNN.

"When the body's active, it develops heat. And you need to generate heat and get rid of that heat. Unfortunately, when it's hot outside, it's harder to do that, so you can overheat and that leads to heat exhaustion and sometimes heat stroke."  

A Phillies spokesman says Halladay would quote- “absolutely” make his next start.
And pitching coach Rich Dubee thinks something besides the heat could have played a part in the reigning National League Cy Young Award Winner's struggles.

"I'm not making excuses, but I've said it before, guys that go to the All-Star Game--and you've got to have the All-Star Game, I understand that--but guys that go to the All-Star Game, they come back a little drawn. It's a busy three days. You look at Beltran now with the Flu. Doc Tonight. So that first week back, guys generally don't respond too well."

The Phillies weren’t the only team sweltering in the summer sun--

Twin Cities’ KMSP reports about 50 people needed treatment for heat related issues Monday during the first game of a Twins doubleheader at Target Field. The Twins supplied free ice water for fans, and a team spokesman says there were no serious problems.

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Transcript by Newsy.