The 3-2 defeat against Arne Slot’s Reds was Fraser’s first appearance since going off injured in a Carabao Cup contest against Stoke City in October.
"Wee Man gives us an attacking threat," said Martin. "He swapped sides in the game and it helped us when Kyle (Walker-Peters) went on the left and he went right.
"They give us that flexibility and Yuki's (Sugawara) been away on international duty and travelled a lot. Then he came back and trained one day with us.
"In a different shape, to chuck him in and after one day's training would have been a bit unfair. We tried to have as many attackers on the pitch as we could."
Flynn Downes was often seen in defence for the Saints which caught the eye of many confused fans but Martin once again explained it was a part of his tactical plan against the league leaders, who struggled despite their victory.
"Flynn's played there in defence for us at Swansea a bit. He ends up building up there a lot as well and he has real pace to defend the transition.
"Against Salah when there was going to be space behind and Cody Gakpo on the other side, I thought he actually did quite well on the whole.
"He mishits one clearance and he gets punished in the Premier League so I'm sure that will get looked at, that decision, but I thought he played really well.
"He stepped forward with the ball a few times and read the game really well and also it's about relationships. We spoke about this a lot.
"He, Taylor Harwood-Bellis and Jack Stephens have played together a lot. Usually, he's in front of them but they've played together a lot."
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