West Ham United entertain Arsenal at the London Stadium on Saturday.
West Ham have taken a number of players from Arsenal down the years, the latest being Jack Wilshere and Lucas Perez.
But rarely do players move in the other direction.
Manuel Pellegrini goes head to head with Unai Emery in a game that promises goals.
West Ham are not in any danger of a relegation battle and Arsenal have to keep winning to push for the Champions League places.
The Hammers were desperately unlucky to lose the reverse fixture 3-1 at the Emirates back in August.
Revenge on the menu for Hammers?
West Ham should have won comfortably that day but were not ruthless enough.
Pellegrini’s side have evolved into a much more competitive outfit since. West Ham have their identity back and sit 10th with a realistic chance of a Europa League spot.
Both clubs look unlikely to do much business in January.
Emery has already stated Arsenal can only bring in loan signings – much to the bemusement of Gunners fans.
And West Ham are believed to be close to or indeed at their Financial Fair Play limit in terms of transfer expenditure and wages.
Two Gunners to become Hammers?
However, two players currently at Arsenal could be swapping clubs for West Ham in the summer.
Left-back Nacho Monreal was signed by Pellegrini during his time at Malaga.
Monreal is out of contract in the summer and is expected to leave the North Londoners. The Spaniard has been linked with the Hammers who have struggled at left-back with Arthur Masuaku suspect defensively and Aaron Cresswell struggling for form and fitness.
Then there is striker Danny Welbeck who is also out of contract at the end of the season.
The England forward is out for the season after another injury. But talkSPORT reports the groundswell of opinion that the London Stadium will be Welbeck’s next destination.
Backwards step for West Ham?
Perhaps a few years ago both deals would have represented good business for West Ham.
But Pellegrini is building a younger, hungrier, more athletic, quicker side.
So both moves look something of a backwards step.
Of course as things stand it is all speculation. It remains to be seen whether Hammers owners David Sullivan and David Gold intend to continue to back Pellegrini with big transfer warchests after the £100 million summer splurge.
If not then perhaps the Chilean will have no other option than to pursue deals like Monreal and Welbeck.