Watene-Zelezniak was subbed off midway through the first half in the Warriors' 12-12 trial draw with Cronulla at Shark Park on Friday night.
The New Zealand Test winger landed awkwardly as he challenged for a high ball and was taken off the field for further assessment.
It was not immediately known whether the injury would impact the prolific tryscorer's involvement in the Warriors' season-opener in Las Vegas.
Fellow winger Roger Tuivasa-Sheck was a late scratching on Friday and the Warriors were also without halves contenders Chanel Harris-Tavita and Tanah Boyd.
The absence of the two playmakers looks to have worked in the favour of Metcalf as coach Andrew Webster searches for a candidate to replace Shaun Johnson at halfback.
Wearing the No.7, Metcalf was lively with ball in hand, nudged an impressive 40/20, and registered a game-high 356 kicking metres.
His exploits came after the Sharks had taken an early lead through in-demand prop Tom Hazleton.
Warriors fullback Charnze Nicoll-Klokstad soon cancelled out the home side's advantage to level the scores at 6-6 to end the first half.
Nicoll-Klokstad and Metcalf combined 12 minutes after the break to send Taine Tuaupiki over on the right edge.
With 20 minutes left, Webster gave Metcalf an early night and replaced him with Jett Cleary, the younger brother of Penrith ace Nathan.
Their father, Ivan, was on hand to watch Jett's first outing in Warriors colours alongside long-time Panthers prop James Fisher-Harris, who got through unscathed.
For Cronulla, the Puru twins - lock Hohepa and halfback Niwhai - looked like they will be pushing for NRL action over the course of 2025.
Hohepa's late try helped secure a draw for the Sharks.
Prop Braden Hamlin-Uele got valuable minutes under his belt and Siosifa Talakai lined up as a right-sided second-rower.
Coach Craig Fitzgibbon kept the Sharks' big guns on ice and will likely let his more high profile names loose in next Thursday's second and final trial away to Canberra.
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