Former Valencia man Hernandez sustained a hamstring problem during the Premier League defeat against Manchester City on New Year's Day and was replaced by Lamah.
Belgium Lamah then suffered an injury blow of his own when he strained an abductor in training, which ensured he has not featured since coming on against Manuel Pellegrini's men.
The Welsh club revealed on their website on Wednesday that both players are making good progress in their recovery and are closing in on a return to the first team.
Goalkeeper Michel Vorm has been sidelined since the draw at Norwich City last month after undergoing knee surgery.
The Netherlands international has revealed the procedure to clear up a long-standing problem was a success, but it is not yet clear when he will return.
"The operation went to plan," Vorm told Swansea's official website.
"There was a little tear in my meniscus, which caused a lot of problems, but a small operation of around 30 minutes sorted things out.
"After a week of the operation, I feel much better than before. I can do almost everything already.
"My knee has a little bit of fluid in it, which is normal at this stage, but I'm very comfortable with my recovery.
"I feel better than how I did before the operation. My knee feels better and my movement has improved, so that's great for me.
"We tried our best to contain it. I missed the Europa (League) game in Switzerland, and I trained fine after that.
"But during the warm-up of the Norwich game I could sense maybe something wasn't right. I'm the kind of player that will battle through it though, and I did for 90 minutes.
"After that game, my knee flared up so we knew we had to get it sorted."
Swansea beat Manchester United in the third round of the FA Cup last weekend and face the same opponents in the Premier League on Saturday.
