Proteas’ opener Alviro Petersen scored a career-best 182 while JP Duminy notched up an unbeaten 48 to help South Africa post a total of 419, before England’s opening batsmen saw the hosts through to 48-0.
“It’s pretty even, I think,” Broad told Sky Sports.
“Being none down for us was vital tonight, and tomorrow morning the first hour will be huge – because we all have one job, and that’s to bat as big and as long as we possibly can.”
The Nottinghamshire bowler, who finished with figures of 3-96, added: “There’s always that expectation and pressure when you win the toss and bowl, that the opposition team won’t get 400.
“But wicket-wise, I don’t think it was that dangerous to bat on.
“It took a fantastic knock from Petersen, with 180. He played and missed a huge amount, but obviously played fantastically well to get there.
“It took that to stop us bowling them out a little bit cheaper.”
Having been buoyed by the late wickets of AB de Villiers and Dale Steyn the previous evening, England failed to make any early inroads in front of a packed crowd despite some tight bowling.
Duminy, batting for the first time in the series, played beautifully marshalling the tail-enders before running out of partners.
Some lusty blows by tail-ender Morne Morkel kept the Western Terrace entertained, however, Anderson wrapped up the innings, removing Imran Tahir for a duck.
Alastair Cook and Strauss saw the hosts through to 48 before the rain settled bringing a premature close to proceedings.
England now face a tough task to vindicate their captain’s decision to insert the tourists in to bat after they scored so heavily in the first Test.
MORE: The latest football news
MORE: The latest tennis news
BIOGRAPHY: Daniel Sturridge
BIOGRAPHY: Kepa Arrizabalaga