Steven Gerrard's arrival as manager of Rangers has focused attention on the other side of Glasgow but Celtic boss Brendan Rodgers' rebuilt reputation is at stake with his former pupil on the prowl.
Rodgers and Gerrard face off for the first time on Sunday at Celtic Park after three seasons together as manager and captain at Liverpool.
Having come agonisingly close to winning the Premier League title in 2013/14, Rodgers was sacked just months after Gerrard's 17-year career at Liverpool came to an end in 2015.
In two years north of the border, the Northern Irishman has won back-to-back domestic trebles, a historic first in Scottish football.
However, the appointment of Gerrard has coincided with Rodgers' first period of strife on and off the pitch at Celtic Park.
The Scottish champions will miss out on the group stages of the Champions League after defeat by AEK Athens in the playoffs and lost for just the fifth time domestically in Rodgers' reign at Hearts in their second league game of the season.
The blame for a poor start to the campaign has largely been pinned on the club's board for failing to back Rodgers.
Despite boasting cash reserves of £30 million ($39 million), Celtic have been too frugal for the liking of their manager and fans during the transfer window.
Celtic have only turned loan deals into permanent moves for French striker Odsonne Edouard and back-up goalkeeper Scott Bain, secured veterans Emilio Izaguirre and Youssouf Mulumbu on free transfers and signed a two-year loan deal for Australian teenager Daniel Arzani from Manchester City.
That contrasts sharply with the cash handed to Gerrard to complete 14 new signings despite Rangers' comparative lack of resources.
- Lack of ambition -
Rodgers himself openly questioned the board's ambition after seeing Hibs midfielder John McGinn join Aston Villa.
"Our job this year was pretty straightforward in terms of bringing players in. We only wanted players of quality," said Rodgers, even before his side were eliminated by AEK.
"We've lost players so the bare minimum we need to do is replace that."
Celtic have even had trouble just holding onto their prized assets. Star striker Moussa Dembele voiced his displeasure via social media after Rodgers confirmed that a bid by Lyon for the French under-21 international had been rejected.
Dembele has played a key role in Rodgers' stunning record against Rangers. In 11 meetings over the past two seasons Celtic have won nine and drawn two, racking up an aggregate of 30-6.
Dembele made clear his displeasure with not being allowed to move, posting on Twitter: "A man, without his word, is nothing. A real man keeps his word."
Even if Dembele stays, Celtic risk having another unhappy player on their hands.
Despite a defensive crisis, Belgian international centre-back Dedryck Boyata refused to play in the second leg away to AEK after Celtic rebuffed reported bids from Fulham before the close of the Premier League transfer window.
Boyata was met with boos and a banner from the club's hardcore element reading "not fit to wear the shirt" on his return to the team, but scored the only goal in an unconvincing 1-0 win over Hamilton to edge Celtic a point ahead of Rangers.
The last time the blue half of Glasgow visited Celtic Park in May, the hosts ran riot in a 5-0 win that sealed a seventh straight Scottish title.
Within a week Gerrard was hired on a four-year contract with the mission to stop Celtic reaching a historic 10-in-a-row.
Sunday will show whether, against all the odds, the former England captain can end Celtic's domination well ahead of schedule.