Unfortunately for him, it took a career-high 123 pitches to get there, and he had to leave after six.
One problem, if it can be called a problem, was that Castillo went to 3-and-2 counts eight times, but he struck out the hitter five times and walked only one.
He pulled a couple of major escape acts to keep the Cubs scoreless.
Alfonso Rivas and David Bote opened the third with back-to-back singles — the number eight and number nine batters in the Cubs lineup.
Facing the top of the order, Castillo promptly struck out three in a row — Christopher Morel, Rafael Ortega and Willson Contreras.
Castillo’s degree of difficulty was steeper in the sixth when he walked the first two Cubs. With two outs, Nico Hoerner beat out a high-hopper to shortstop, filling the bases.
Castillo was at 115 pitches and Joel Kuhnel was ready in the bullpen, but Reds manager David Bell opted to permit Castillo to stay.
Once again he went to 3-and-2, but induced a routine fly ball to left field from Yan Gomes.
Fortunately for Castillo when he left the Reds had constructed a 5-0 lead.
Castillo and Cubs starter Keegan Thompson engaged in a tight pitcher’s argument for five innings, a scoreless tie.
Thompson came into the game with a 7-2 record and had given up only one earned run in his previous two starts. And he held defending World Series champion Atlanta to no runs and three hits over six innings two starts ago.
The Reds broke through in the sixth for two runs on a single by Aramis Garcia and back-to-back doubles by Brandon Drury and Donovan Solano.
The lead expanded to 5-0 in the seventh on Jonathan India’s three-run home run off Cubs relief pitcher Rowan Wick.
It was India’s fourth hit in his last 31 at bats and it followed singles by Albert Almora Jr., and Nick Senzel.
Now it was up to the Reds bullpen, always a disaster peeking its ugly head from around every corner.
And it happened. Kuhnel quickly gave up three runs, cutting Cincinnati’s lead to 5-3.
Rivas led off with a single and Kuhnel hit Bote with a pitch. Morel drove one to right center. Center fielder Senzel looked at right fielder Almora and Almora looked at Senzel and the ball fell for a run-scoring double.
Ortega grounded to second as the second run scored and Contreras beat an infield single to plate the third run.
Kuhnel finally ended the mess by getting Reds-killer Ian Happ on a ground ball and by striking out Patrick Wisdom on a full count.
Art Warren replaced Kuhnel for the eighth and Hoerner immediately singled to right. Warreb squeezed out of trouble on a fly ball to right, then a running catch in right by Almora on a hard line drive by Rivas and a pop up.
Now it was closing time and Hunter Strickland was asked to put a lock on this one in the ninth. He struck out Morel, the fourth time Morel struck out. But Ortega doubled off the right field wall and the Cubs brought the potential tying run to the plate.
Contreras popped to third on a 2-and-0 count for the second out. That brought up Happ, owner of 24 career homers against the Reds. He popped to shallow left to Matt Reynolds to end it.
The top three batters in the lineup — India, Drury and Solano — combined for six hits (two each) and drove in all five runs. Garcia chipped in with a three-hit night.