Klaasen won the Player of the Match award for his unbeaten 74 off just 65 deliveries in a match reduced to 40 overs due to rain. His superb partnership with David Miller (75 not out of 63) laid the platform for his team's nine-run win in Lucknow.
He walked out to bat in a pretty tricky situation when the Proteas had just lost Aiden Markram and were in a spot of bother at 71/3. Indian bowlers Kuldeep Yadav and Shardul Thakur were in the middle of a great spell and both were getting plenty of help from the pitch.
This made Heinrich Klaasen even more satisfied with his knock as he weathered the storm and then cashed in towards the end of the innings. In a video posted by Cricket South Africa (CSA) on their Instagram handle, here's what Klaasen had to say about his and South Africa's performance:
"Very pleased to be having scored runs in these conditions. We have been working over the past couple of years to get these options right and it paid off so very pleased about it. One of the better innings that I have played. It was tough. The ball was spinning quite a bit and nipping around."
Heinrich Klaasen on his crucial partnership with David Miller
David Miller continued his rich vein of form from the T20Is against India into the first ODI as he scored an unbeaten 75.
Miller added 139 runs for the fifth wicket with Heinrich Klaasen. The southpaw provided the much-needed impetus to the Proteas' innings and provided the finishing kick that took them to a match-winning total.
Here's what Heinrich Klaasen had to say about his partnership with Miller:
"Love batting with Dave (Miller). He keeps me nice and calm. Knowing that such a powerhouse with the bat is standing on the other side takes a lot of pressure off you as a teammate."
"The way he plays and the tempo at which he plays just makes it a lot easier. His form is impeccable at this moment and the way that he is hitting the ball."
South Africa need to win the series to give themselves the best-possible chance of direct qualification to the ODI World Cup in India next year. They will look to seal the series when the two teams meet in the second ODI at Ranchi on Sunday (October 9).