The NRL are investigating a second-half conversion attempt by Nathan Cleary that sees a Parramatta trainer run across the field and in front of the goals during Friday night's clash between the Panthers and Eels.

Cleary's kick would direct waywardly to the right of the goalposts, seeing the Penrith captain fail to convert a Taylan May try, with the missed opportunity the difference in the 22-20 scoreline.

The incident in question occurred in the 53rd minute, with a trainer leaving an Eels huddle and scurrying across the BlueBet Stadium field toward his side's interchange as Cleary began his attempt.

“We are aware of the incident,” NRL head of football Graham Annesley told News Corp.

“It will be looked at further as part of our normal review of the weekend of football on Monday.”

Parramatta are understood to have stated that the trainer's actions were not deliberate, however the league could still look to hand the Eels a breach notice.

NRL guidelines dictate that "trainers must not at any time enter the line of sight of a player when he is attempting a kick for goal, or do anything which may in any way unnecessarily interfere with or distract an opposition player whilst he is participating in the match or constitute some disadvantage to the opposing team.”

The incident will be a key point in Monday's footy briefing, with a decision by Annesley to land in the coming days.

Friday's loss was Penrith's first defeat of the season, with their place atop the NRL ladder now under threat from a surging Melbourne side.

A win over the Dragons on Sunday will see Craig Bellamy's side sit first overall ahead of a highly-anticipated clash between the two 2020 grand finalists next Saturday in Magic Round.