Byrne allows Lions to focus on positives
The Royal XV were supposed to be easy prey, but they almost savaged the tour hopes of the Lions.
Defeat against a side drawn from the third tier of South African rugby would have dealt a devastating psychological blow to Ian McGeechan's men.
Victory allowed the tourists to focus on the positives despite an unconvincing display.
Defence coach Shaun Edwards argued his side had "fought very, very well in the second half", while skipper Paul O'Connell was pleased his side had been given "a bit of a wake-up call".
Byrne was the catalyst for the Lions resurgence, scoring an opportunistic solo try just two minutes after Riaan Viljoen had put the home side 25-13 ahead.
The Wales full-back was the game's outstanding player - secure under the high ball, booming with his boot and impressive in attack. Edwards described him as "superb, outstanding" and the Ospreys star looks nailed on for a Test spot.
Byrne linked well with his Wales team-mate Shane Williams, who made some superb runs from deep and looks ideally suited to the hard grounds of South Africa. Another Welshman, centre Jamie Roberts, also emerged from the game with credit, after some powerful runs in midfield.
O'Gara was flawless with his goalkicking and showed a cool head at the close, while Tommy Bowe was effective with what little ball he had and took his try well.
McGeechan said he wanted to use the game to look at combinations as well as individual performances. The front row certainly had the measure of their opponents at the scrum and Welsh duo Adam Jones and Matthew Rees will have further impressed coach Graham Rowntree.
There is certainly the possibility of an all-Welsh front row - if you add the outstanding Gethin Jenkins - taking on the Boks in the first Test in three weeks' time.
On the flip side, Keith Earls and Mike Blair had a horror show in the first half and could find their game time limited now. Earls, the young Munster centre, looked nervous and seemed to be trying too hard.
He knocked on several times early in the game and spilled a high ball in the 16th minute, leading to the Royals grabbing their opening try. The fact that Riki Flutey made a big impact after replacing him will have done little to make the Irishman feel any better.
Scotland skipper Blair was caught in possession a couple of times and many of his passes were poor. On such a short tour, players can ill-afford to put in poor performances, as Andrew Sheridan, admitted on the eve of the game.
The massive Sale prop, who was effective in the scrum but quiet in the loose, said: "If you don't play well, you're not going to be starting in too many more games."
The Lions' biggest problems were a lack of ferocity at the breakdown and numerous errors. O'Connell alluded to this at the end of the game, when he said: "You have to remember the physicality and attention to detail you have to bring to a rugby match."
Much of the blame for the lack of impact at the breakdown must go to the back row of Martyn Williams, Joe Worsley and David Wallace.
Williams made some amends with an excellent off-load for O'Gara's try, but Wallace made errors at the base of the scrum and Worsley was largely anonymous.
Eight of the starters were making their Lions debuts and Edwards suggested some had been nervous. He also pointed out that some of the team hadn't played for a month, while "the effects of altitude were also a bit of a shock" for them.
The side won't be able to afford to play so poorly again. Next up are Super 14 outfit the Golden Lions at Ellis Park in Johannesburg on Wednesday. It is set to be a 61,000 sell-out, which will be quite a contrast to this game played in front of a two-thirds empty stadium in Phokeng.
And they will be expecting to take a famous scalp after watching the Lions' faltering opening performance.