The defender admitted he suspected he was offside for the side's controversial second goal, while dedicating the win to under-fire coach Jens Keller
The pressure was on the Gelsenkirchen club to secure a place in the last 16 with victory over the visitors, after reports claimed coach Jens Keller would be sacked if his side were dumped out of Europe.
Second-half goals from Julian Draxler and Matip ensured second spot in Group E behind Chelsea and ahead of Basel and the defender hopes that his strike can help Keller stay on at the Veltins Arena.
The 22-year-old told Sky: "I was watching the linesman with one eye and I was suprised that the referee did not whistle.
"We knew what was at stake. This victory was also for our coach. It is a difficult time for him right now. We want to continue working hard and try to be more consistent with our performances."
Schalke was beaten by Hoffenheim in the DFB-Pokal last week and sits sixth in the Bundesliga, but Keller will have another shot at strengthening his position when his side hosts Freiburg this weekend.