Wales prop Wyn Jones grabbed his first Lions try and England’s Owen Farrell kicked a conversion and two penalties although it wasn’t enough to stop a 17-13 defeat.
South Africa’s A side was a virtual full-strength Springbok outfit and their starting team contained 11 players who began the country’s victorious 2019 Rugby World Cup final win over England.
Tries from Sbu Nkosi and Lukhanyo Am gave the hosts a 14-point lead after a powerful first-half display and it was an advantage they held on to despite a Lions comeback.
Gatland said: “The players are bullish in the changing room. They believe we can handle anything that is going to be thrown at us. It’s definitely a game we needed.
“We will take a lot out of tonight. South Africa started well and were very physical at the breakdown.
“We came to terms with that so I’m proud of the boys from 17-3 down to come back and finish so strongly.
“It goes to show these Test matches are going to be a real arm-wrestle.
“South Africa did a lot of the things we expected. They kicked a lot and were very aggressive and direct with their running, particularly in that first half.
“What I was pleased about was our set-piece. We scrummed outstandingly well.”
The Lions were forced into two late changes before kick-off. Wales wing Josh Adams was withdrawn to attend the birth of his first child by Zoom.
Liam Williams came in with Anthony Watson switching to the wing. Wales fly-half Dan Biggar was deemed not fit to start due to a small ankle knock. Farrell started instead.
The strength of South Africa’s A side was always going to make this the Lions’ toughest test on tour so far and so it proved.
Giant Springbok lock Eben Etzebeth immediately crashed into Williams summing up the home side’s physicality. South Africa also targeted the breakdown impressively.
Their first try came when Etzebeth charged down Farrell and Nkosi was the beneficiary as he ran away to score.
Am added a second after being set up by the dancing feet of outstanding South African wing Cheslin Kolbe.
Veteran Morne Steyn – who faced the Lions on their last tour of South Africa in 2009 – kicked both conversions.
At 14-0 down the Lions were in trouble, but their set-piece was solid with Jones superb alongside the England pair of Maro Itoje and Tom Curry.
Penalties from Farrell and Steyn meant South Africa A led 17-3 at the break, but the Lions had forced both Faf de Klerk and Marco van Staden to suffer yellow cards for infringements on their own line.
The Lions had to strike with a two-man advantage and they did when prop Jones rumbled over at the start of the second period.
Farrell converted and added a penalty to set up a grandstand finish and Wales wing Louis Rees-Zammit came close to a late winning try as he looked to dive over in the corner.
But he didn’t make the line and the Lions fell short.
They will be boosted though by the return to the tour of Alun Wyn Jones in the next few days while Ireland hooker Ronan Kelleher has also been added to Gatland’s squad.