Arsenal confirmed the capture of the Brazilian centre-back recently for a reported fee of £11.2 million, finally answering long-term calls for Arsene Wenger to strengthen the heart of his defence.
Naturally, however, the 24-year-old's signing raises questions about Wenger's starting XI. Does Gabriel slot straight into the Arsenal side or does he start on the bench and wait for his chance?
Should Wenger opt for the former, who then misses out?
The obvious choice, perhaps, based on form, would be German defender Per Mertesacker, who has struggled to match his previous heights with the Gunners this term.
And Arsenal icon Keown certainly sees it that way - suggesting Mertesacker's place in the side will be under far more scrutiny than Laurent Koscielny's.
"I think for Mertesacker there’s no room now for any indifferent performances, because he has had a few and still been in the team," the former centre-back said during a 'Tackle Keown' session on the Daily Mail's website.
"There’s been a few times this season when he hasn’t been dominant or mobile enough. The question marks are over Mertesacker rather than Koscielny."
The added pressure, though, could work in the 30-year-old's favour, according to Keown.
It will certainly benefit Arsenal, he argues, as it will encourage Mertesacker to produce nothing but stellar performances should he aim to keep his place in Wenger's team - something he feels could be important enough to get the north London side into the top four.
He added: "The German needs a dozen outstanding games to keep his place but, if he does, Arsenal will end up in the Champions League. And that’s the effect you want from any new signing. You want them to improve everybody’s performances."