The centre-back played 45 minutes against Stoke on Saturday, before then starting again against Coventry the next day and only lasting 30 minutes before limping off.
And although he admits he took a risk with Mosquera and others with the packed schedule, Lage is happy with the intensity he is putting on the players.
When asked for an update on the injuries to Willy Boly and Mosquera, Lage said: "We need to wait. It’s part of the process. We are training hard with a different way to work.
"Also, with Yerson, he came from Colombia after a long time without training. These kinds of things can happen.
"We put all the guys at risk playing nine games in five days, but with three weeks to prepare for the season I prefer to take that risk.
"The guys who survived these four or five weeks are at a good level to start the season.
"Imagine, (Conor) Coady comes, works one day with us and the next day he played 70 minutes against Al-Shabab and against Stoke he played 90 minutes. Nothing happened with him.
"Sometimes it can happen, but I preferred to take the risk. They should be ready within three weeks and we need to grow up with training and with games."
Meanwhile, Lage insists he is very happy with Mosquera and has praised his scouting team for identifying his talent.
He added: "Fantastic work from the chief scout and the guys who work with him. When I was here, I said what the squad needed to grow up. They found the kid, they gave him to me and what I saw was good.
"We did a good job, not just me but them. We found a player and we brought him. If you ask all the guys, they love Yerson.
"But he needs time also. He did well in the first game but he needs time to adapt. Everything is new for him."