The goals were Long's first in the Premier League for Saints.
"Obviously, I'm delighted," he told the Southampton club website.
"The main thing was getting three points.
"To be fair to Leicester, they put in hard work for the whole game, trying to keep us out, and Sadio (Mane) and the lads were really tiring out their defence, and that kind of gave me the opportunity to come on with fresh legs to try and cause them problems.
"Luckily, the chances fell my way, and it was nice to see them hit the back of the net."
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