The phrase "an opening stage" is correct and usable in written English.
It can be used to refer to the initial phase or part of a process, event, or performance.
Example: "The play begins with an opening stage that sets the tone for the entire performance."
Alternatives: "initial phase" or "beginning stage".
He understands a dialogue as an exchange made up of an opening stage, an argumentation stage, and a closing stage.
All 198 riders are going to be on that start line on day one knowing they have got a chance of taking the yellow jersey, which is a once in a lifetime chance for most of them, so it is going to be one heck of an opening stage.
All the riders made it safely through the tight final bend on a greasy surface as the entire field survived what had been a testing day in often soaking conditions, a day after Dan Martin's hopes were ended in an opening-stage crash.
Mark Cavendish's dream of claiming his first Tour de France yellow jersey disappeared because of a crash near the end of a farcical opening stage.
After a problematic opening stage, Contador had been shadowing the other favorites closely for the first week and a half of this Tour, a pattern that continued until the final seconds of the 12th stage Thursday.
This beneficial effect of ethylene pretreatment was manifested at two different stages of pollen development: 3 days before flower opening (stage A-3) and at the mature pollen stage (A), suggesting ethylene's involvement in thermotolerance of developing/maturing pollen grains as well as in pollen germination, respectively.
The thematic hubbub of the play's first ten minutes, which document the precariousness of the settlers' lives, creates a somewhat smudged opening stage picture that becomes clear when Liam Neeson makes his entrance as John Proctor.
Thomas helped Froome to the Tour title in 2013 in spite of suffering a fractured pelvis in a fall during the opening stage.
The thrilling Edvard Munch exhibition at Tate Modern in London includes a room devoted to the Norwegian artist's work in theatre, and the sculptor Antony Gormley has on show at Castle Coole in Enniskillen a work called Godot Tree – Gormley's interpretation of the opening stage direction ("A country road. A tree. Evening").
De Backer sought to go it alone inside the final 6km but was soon caught, as was BMC's Greg Van Avermaet, among the pre-race favourites for the general classification, before losing more than a minute on the opening stage.
The double Olympic gold medallist suffered the injury in a crash in the opening stage on Saturday.
