The phrase "decisive phase" is correct and usable in written English.
It can be used to describe a critical or determining stage in a process or situation.
Example: "The project has entered a decisive phase where key decisions will shape its future direction."
Alternatives: "critical stage" or "pivotal moment".
Myanmar is entering a decisive phase in its political transition.
Bulgaria's presidency will coincide with the decisive phase of Brexit negotiations.
The former speaker's presidential campaign is now in its fourth and potentially decisive phase.
The battle for the country's presidency appeared to be entering a decisive phase.
THE battle for eastern Ukraine may be entering a decisive phase.
Pakistani military officials said that the offensive against the Taliban in Swat had entered a decisive phase.
The term Final Four has now been borrowed by European professional basketball leagues, team handball tournaments and Italian volleyball competitions in describing their decisive phases.
But anybody writing the history of the 20th century in Britain will regard Thatcher as one of the dominant political personalities, and her era as one of the decisive phases in our history.
CAPE TOWN — Though simply saying "The Dutch" will bring a smile to the lips of many a lifelong soccer fan, the reality is that the Dutch have made a national rule of faltering in the decisive phases of the World Cup.
The two offensives - one by the Syrian army with Russia's support, the other led by Turkey with allied Syrian rebels - entered decisive phases this week.
This is one of the most decisive phases in the entire malaria transmission cycle; the vast majority of parasites are lost during this process, mostly due to robust immune reactions mounted by the mosquito host, and indeed only few parasites survive to continue the transmission cycle.
