American fighter Terrance McKinney scored a 7-second knockout in a breakout UFC debut

• Terrance McKinney just scored a seven-second knockout on his UFC debut.
• The American was brought in on a late assignment and celebrated in style until he injured himself.
• Watch the finish right here.

Up-and-coming American fighter Terrance McKinney scored a seven-second knockout in a breakout UFC debut Saturday at the Gila River Arena in Arizona.

The 26-year-old was so elated with the lightning-fast finish that he injured himself during an over-exuberant celebration that involved an attempt at mounting the Octagon fence.

He appeared to damage his knee, and was seen leaving the cage requiring assistance.

McKinney was fighting lightweight opponent Matt Frevola just one week after winning in 72 seconds, brought in on a late assignment at UFC 263 - one of the UFC's big pay-per-view events of the summer.

The match had barely even begun when McKinney threw the best one-two punch combination of his career.

The first, a distance-measuring right-hand jab from the southpaw position, was followed by a stinging and straight left hand that landed hard, fast, and accurately on Frevola's chin.

Frevola immediately dropped the canvas in a heap, but McKinney wasn't done.

The Warrior Camp athlete pounced on Frevola and hit him with a hammer-fist to the face, then again, and again, before the referee saved Frevola from further punishment.

Watch the knockout right here:

Saturday's showdown was McKinney's 14th MMA match as a professional.

He competed earlier this month June 4, icing Michael Irizarry with punches in the opening round.

His latest victory advances his MMA record to 11 wins (five knockouts, six submissions) against three losses.

It is currently unclear how injured his knee is, or when he will be able to return to ultimate fighting.