An amateur goalkeeper taught this to me in a 6X6 game when I was playing as a defender. This is actually basic defending in 2 on 1 situations.
Then he was a terrible goalkeeper giving terrible advice.
It is correct in 99% of occasions to go to the man with the ball if he is clean through and NOT to cut his passing option. If you don't, then the man in possession has a free shot on goal. You want to challenge the ball. The striker may fluff his pass or the shot as a result of the challenge. It's all about playing the percentages. You absolutely do not run away from the ball when you are the only defender up against two attackers.
The ONLY time you do not do this is if the man in possession is really really shit at finishing and the other guy is very good. Sissoko/Son being the case in point here and the 1% exception.
ofc. If I've misread your intention and you were agreeing with me, then ignore this.