Arsenal midfielder Ramsey had been nursing an ankle injury, while West Ham centre-back Collins has been sidelined by a knee problem.
Swansea full-back Jazz Richards and Brighton midfielder Andrew Crofts have been called up as replacements, with the FAW confirming their additions in an updated squad list on their official website.
Tottenham winger Gareth Bale remains part of Coleman's squad despite increasing speculation over his future, with Spanish giants Real Madrid reportedly ready to break the world transfer record to secure his services.
The 24-year-old has not played for Spurs in nearly a month, but is expected to play a part when Wales train at their Newport base on Monday afternoon.
- Sports & Recreation
- Jazz Richards
- Gareth Bale