Leach, who has played in all 13 England Tests since Ben Stokes took up the captaincy in April last year, has been ruled out of this summer’s series due to a stress fracture in his back.
England open their bid for a first Ashes win since 2015 at Edgbaston on 16 June, following on from last week’s resounding 10-wicket victory against Ireland.
Former Australia captain Smith, who has spent the last month playing for Sussex in the County Championship, feels Leach will be a tough act for any replacement to follow.
“I watched little bits and pieces (of the Ireland Test), England played pretty well,” said Smith. “Obviously the news of Leachy broke yesterday. It’s a real shame, he’s done really well for England the last 12-18 months in particular.
“I think it’s going to be some big shoes for them to fill. Obviously (I) feel for him, he wants to be involved in the big series, an Ashes series. Hopefully he recovers well.”
Australia have the World Test Championship final against India at the Oval to come before the start of the series, with play due to get under way on Wednesday.
We’re all with you, Leachy.
— England Cricket (@englandcricket) June 4, 2023
And Smith insisted the tourists will fully focus on that before turning their attention to a first Ashes win on English soil since 2001.
He added: “I’m just playing each game as it comes. I’m not even thinking about the opposition too much, just going out and playing the game. That’s really it to be fair.
“We’ll get through this game then start focusing on England after that. We’re all just looking forward to this (India). It’s two years in the making, of getting to the final of the World Test Championship, it’s a big week for us and India, so we’ll get through this then we’ll focus after that.
“Every game you play for your country is important. Every series is important. Certainly the Ashes series here, it’s one that eluded us, we’ve never won here. We got close last time but couldn’t quite get over the line. It’s certainly something I’d love to tick off my bucket list, winning an Ashes series here.”
The India Test will be a chance for Smith to add the top prize in red-ball cricket to the one-day and T20 World Cups he has won with Australia.
Asked whether he felt Test cricket was under threat from proposed changes within the game and talk of possible franchising, he said he believed recent matches have emphasised the popularity and importance the format still holds for fans.
He added: “In terms of one-day cricket, obviously the World Cup is the biggest tournament in white-ball format but it’s still a while away so we’ll focus on that later. It’s certainly one that we want to win as well.
“Hopefully Test cricket stays alive and well, I think it’s in a good place at the moment. Some of the games we’ve seen recently have been pretty amazing.
“For me as a traditionalist, someone that loves Test cricket, I hope it still remains at the front of all the boards’ minds and stays alive and well for some time to come.
“(The World Test Championship) is really important. Having the two best teams play in the final I think is great. It adds a bit more relevance I suppose to Test cricket, it’s what we all work towards for a couple of years. This week should be an exciting one and the guys are looking forward to it.”