After two-and-a-half seasons on the sidelines due to injury, Klay Thompson is savouring every moment before the Golden State Warriors face the Boston Celtics in Game 5 of the NBA Finals on Monday.

The Warriors were on the verge of forcing a Game 7 against the Toronto Raptors in the 2019 NBA Finals, when Thompson tore the anterior cruciate ligament in his left knee with two minutes remaining in the third quarter of Game 6.

On 28 points at that point on eight-of-12 shooting, he ended up sinking both free throws before being forced off the court and did not return for the Warriors until January this year, missing the whole of the 2019-20 and 2020-21 seasons.

Monday is the three-year anniversary since that game but ahead of Game 5 against the Boston Celtics, Thompson revealed he did not realise the extent of his knee injury and had only one thing on his mind.

"I never had such a severe injury, so I didn't think it was that serious," Thompson said. "I thought I might have sprained something in my knee, but when you're playing in front of your fans, your adrenaline is so high, you kind of disregard anything that makes sense.

"Running around on a torn ACL doesn't make very good sense. I just thought, 'I don't want to leave these points on the board, man. This is the Finals, I'm going to go get this 30-ball.'

"On top of that, I went to the back, and they did a little test, and they came out with the conclusion that I should probably put some crutches on. Wow, what a time, three years ago. It goes by fast."

The 32-year-old has been in patchy shooting form over these playoffs and hit a nadir in the opening two games of the NBA Finals, going a combined 10-of-33 from the floor.

Thompson found his feet as the Warriors evened up the series in Game 4, coming up with big shots on the way to 18 points and 40 per cent shooting from the perimeter.

Playing in his sixth-straight NBA Finals on an individual level, following that absence due to injury, Thompson is not taking the magnitude of the occasion for granted.

"Man, it seems routine, but I know how special this is," he said. "I mean, I'm trying to just be present in everything I do during this time – even this interview. Not even looking ahead to tomorrow but just enjoy this day before the big one.

"I mean, the NBA Finals is such a cool thing to be a part of. I remember being in Istanbul, Turkey in 2013, doing some stuff for the NBA and waking up real early just to watch it. To realise that these games are broadcast worldwide just reminds you how special it really is.

"I know when my dad [Mychal] played back in the day, the NBA was not as global so to be here now, it's special."