He may not have wanted it but Heinrich Klaasen can recognise he had a front-row seat to one of the smoothest T20I innings the game has seen, as Babar Azam notched up his first century in the format, and added 197 for the first wicket with Mohammad Rizwan, to ease Pakistan through their highest successful chase.

"It was something [to see] from behind [the stumps]," Klaasen said. "We tried a lot of things. We tried to go death [bowling] early to them because they were hitting the ball nicely. They made a lot of good balls that were well-executed look bad by very good placement and strokeplay."

Klaasen introduced Lizaad Williams, whom he has previously identified as one of his end-of-innings bowlers, in the fifth over, and with some success. Williams conceded just four runs after the new-ball pair of George Linde and Beuran Hendricks had given away 42 in the first four overs. That blazing start included what may be the classiest shot Azam has played on this tour so far, off Hendricks, when he opened the face of the bat at the last millisecond to run the ball wide of short third man.

Despite that, Hendricks was given another over which began with Azam breaking his bat off the same ball he hit for six, and ended up costing 18 runs, in an early sign that South Africa would run out of ideas. "It was difficult from a captaincy point of view to try a lot of things because on a wicket like that you don't want to try too many things," Klaasen said.

One of the things South Africa didn't try was using another of their death-bowling specialists, Andile Phehlukwayo, who has only bowled two overs in the series to date. "His confidence is a little bit low but he is picking it up and I had no need for him," Klaasen said. "We've got specialist guys in the positions."

But the specialist guys were not able to pull off their specialities, such as Tabraiz Shamsi, whose task is to take wickets in the middle overs. Though he didn't concede a boundary in his first over, Shamsi did not threaten at all, and by his third, Azam was ready to take him on. He pulled a long-hop for six before driving a tossed-up ball through the covers to bring up a century off 49 balls. "Babar has a special manner," Klaasen said. "When a guy like that comes off, it's very difficult to defend on this ground."

Maybe the best method of defence was attack and the only way for South Africa to win the game was to dent Pakistan's chase with dismissals but, as Klaasen put it, "the question is how do you take wickets on pitches like this? There's no turn, the wicket is skidding on, the slower balls are not gripping, and the ball travels [through the air] at the Highveld. It's difficult to strike. So the way you get your wickets is to be defensive and make sure they can't bat easily at 10 an over like they did tonight."

Or to get the batsman to make a mistake in reaching for a wide delivery, like Hendricks did against Mohammad Rizwan, who did not get enough bat on it and sent a chance to Pite van Biljon at backward point. Van Biljon put it down. "We have were very poor in the field as well tonight," Klaasen acknowledged.

Overall, South Africa have been no worse than Pakistan, who dropped five catches in the ODIs and four in the T20Is so far. South Africa have spilled four in each format, but as an outfit that prides itself on this discipline, that simply isn't good enough. "We try not to be so bad in the field and at training we are brilliant. It's guys maybe trying too hard and not being calm enough in the field," Klaasen said. "It's been a trend that we have to get rid of."

So is their record in defending big totals. Three of the four highest successful T20 chases have come against South Africa, while Pakistan have reached the highest and second-highest T20I targets in this series. Although Klaasen has not played in all of those matches, he was part of the team that England chased 223 against at the same venue last year. The conditions may have something to do with why South Africa have struggled even when they put big totals on the board, but Klaasen was careful not to blame the surfaces and rather pointed the finger at the South African line-up. "We were about 10 runs short," he said, perhaps a conservative estimate since Pakistan won with two overs to spare. "It's a very good wicket and we had both openers going past 50. We are guilty in that not one of the guys over the last three games, the guys that scored runs went on to be there at the back end like the Pakistani batters."

Aiden Markram racked up his third successive fifty in this format, Janneman Malan recorded a career-best 55, and the pair shared an opening stand of 108, but were both dismissed in the third quarter of South Africa's innings. In the end, their milestones will lurk in the shadows of a much bigger achievement: Azam's first T20I ton and Pakistan ensuring they have one hand on the trophy. As Klaasen put it: "Tonight it was just a case of some brilliant batting from their side."

Firdose Moonda is ESPNcricinfo's South Africa correspondent