Tierney has missed Arsenal’s last six games with a knee injury, but wasn’t deemed fit enough to be named in the squad for the Gunners’ Premier League clash away at Newcastle on Sunday.
While Lacazette has been missing since the 1-1 draw with Fulham last month, having not fully recovered from a hamstring injury.
“They haven’t trained with us yet,” manager Mikel Arteta told Sky Sports ahead of the Newcastle match.
“So it’s unlikely to have them ready in the next few games.”
However, both players took part in a full training session on Tuesday afternoon ahead of the game, meaning that they are likely to be in contention for the crucial European encounter.
Do you want all the latest news from around Arsenal Football Club straight to your email inbox?
Of course you do.
By signing up for our Arsenal newsletter, you will receive a twice-daily email, focused on all the latest news from the Emirates Stadium.
And, not only that, but you will get exclusive content from our club writers Chris Wheatley and Kaya Kaynak before anyone else.
You won’t miss a thing when it comes to the Gunners.
How do you sign up?
It’s easy and only takes seconds.
Simply type your email address into the box at the top of this article – or any article on the Arsenal section of football.london in fact – labelled ‘Get the biggest daily stories by email’ and click ‘Subscribe’.
Alternatively, you can click here and tick the Arsenal box to subscribe for our Gunners newsletter.
If you decide later that you no longer wish to receive the emails, simply follow the unsubscribe link in one of the newsletters – but we don’t think you’ll want to.
But the Gunners were dealt a blow when Luiz was forced off with a hamstring injury in the second half, although early signs are positive and it’s not expected to end the Brazilian’s campaign.
After the Europa League semi-final Arteta’s side face Premier League matches against West Brom, Chelsea and Crystal Palace, before finishing the league campaign with a home game against Brighton on May 23.