Kyle Sinckler

Sinckler is one of several players, such as Owen Farrell, Jamie George, Manu Tuilagi and Courtney Lawes, who have passed their 30th birthday.

Jack Willis, David Ribbans, Henry Arundell and Joe Marchant will play in France next year and may be ineligible.

"It has been mentioned - the 'last dance'. It makes everyone aware how special this is," said Sinckler.

"It will never happen again."

Ireland's Porter, 25, suffered a toe injury as Leinster lost to Glasgow in the Pro14 Rainbow Cup on Friday.

Sinckler, who toured New Zealand with the Lions in 2017, will join the squad at the end of Bristol Bears' season.

The prop, 28, gave an emotional television interview in May after not being selected for the Lions.

Speaking after his man-of-the-match Premiership display for Bristol against local rivals Bath, Sinckler said his omission from the squad "had been tough" because it "meant so much".

Tighthead Sinckler, 24, was returned to his upmarket hotel in a police car hours early on Sunday after police attended an incident involving "minor disorder" in central Auckland.

"A male was placed under arrest but was not charged after further inquiries established that the incident did not warrant prosecution," police said.

It is understood the incident took place on Galway St in central Auckland about 3am.

Hours earlier the 122kg Sinckler had come on in the third test at Eden Park, with the 15-15 draw earning the British and Irish Lions a share of the series.