The Exeter Chief was a late comer to international rugby making his debut in the first Test against the Springboks as a 29-year-old but immediately seemed at home in the cut and thrust environment.
Johnson would start the next two matches in the series, which England lost 2-0, and is the man in the possession of the blindside berth heading into the autumn internationals.
Croft will only just be returning to fitness then after injuring his neck for Leicester against Harlequins in April having started all of England's RBS 6 Nations matches.
And he concedes he will have a fight on his hands to wrest the jersey off Johnson.
"No-one likes to see someone else wearing your shirt but my focus has to be club rugby and getting myself back fit as soon as feasibly possible," said Croft, who is a an SSE ambassador.
"At the moment I don't know when I'll be coming back from the injury. I'm definitely not going to be back in time for the start of the season with Leicester.
" I'm back in the weights room which is good, but in terms of full practice and then getting back to competitive rugby, it's hard to put a time frame on it.
"I thought Tom did really well down in South Africa, there is not a harder place to play international rugby, let alone make your debut and he stood up to it well.
"Everyone in the game of rugby knows that quality that he brings, he was outstanding for Exeter this season so it's no surprise to me how well he coped.
"He carried the ball well at times, made his tackles and put himself all over the park, all of which are the vital things you want from your six so he deserves a lot of credit.
"He's really put his hand up for future selection and it's going to be a real battle for places come the Autumn internationals but he has had his test and come through it.
"But competition for places is great, Stuart is bringing through new players in every position and this is what we want, lots of players with experience at this level that will stand us in good stead moving forward."
PLEASE LEAVE IN FINAL PAR - To hear more from Tom Croft and be in with a chance of winning £10,000 worth of energy credits for your club, simply register here: www.sserugby.com