Du Plessis did not play in England's crushing 211-run win in the first of a four-test series at Lord's last week following the birth of his first child.
But he was on hand to see South Africa lose 10 wickets in under two sessions as they slumped to 119 all out in their second innings with more than a day to spare.
"I had the baby with one arm and watched the cricket with one eye," Du Plessis told reporters at Trent Bridge on Thursday – his 33rd birthday and the day before the second test starts on Friday.
"I saw a lot interesting things from the side which is probably a bit of outside perspective, you don't always get that," he added as he took back the reins from stand-in skipper Dean Elgar.
"I'm really excited to be back with the team. It was tough going for us, the previous one, we weren't as good as we would like to have been but in cricket you get another go and we're looking forward to this next test."
South Africa have a proud away test record. In their past 19 series spanning some 10 years on the road, they've won 13, drawn five and lost just one – in India in 2015/16.
But they did not help themselves at Lord's by twice taking wickets with no-balls and missing several chances to dismiss Joe Root before he marked his first innings as England captain with a brilliant 190.
"It's basics for me, there's no point looking too much further as you can over-analyse," said Du Plessis.
South Africa did manage to reduce England to 76 for four on the first morning at Lord's before the hosts fought back, aided by some slack Proteas fielding.
"There were times that England found themselves under pressure – the disappointing thing was just how quickly they got out of it," said Du Plessis.
"It's basics for me, there's no point looking too much further as you can over-analyse," said Du Plessis.
South Africa did manage to reduce England to 76 for four on the first morning at Lord's before the hosts fought back, aided by some slack Proteas fielding.
"There were times that England found themselves under pressure – the disappointing thing was just how quickly they got out of it," said Du Plessis.
