The Baggies picked up a surprise draw against Liverpool two games ago, but then were brought firmly back down to earth by Leeds who hammered them 5-0.
They remain five points from safety so they are not cut adrift yet, but Sam Allardyce must start picking up points soon.
Arsenal have moved away from being surprisingly close to the relegation zone with back-to-back wins over Chelsea and Brighton.
It is progress for Mikel Arteta, but his side are still just 13th in the table and will be hoping for much better to come.
The match kicks-off at 8pm on Saturday 2 January at the Hawthorns.
BT Sport 1 will be showing the game live with coverage starting at 7.30pm.
Subscribers can stream the action on BT Sport Player or on the BT Sport app.
West Brom are without Jake Livermore through suspension and both Conor Townsend and Kieran Gibbs through injury, although Kyle Bartley and Hal Robson-Kanu should be available.
Arsenal are still missing Gabriel and Thomas Partey, but Mikel Arteta has Bukayo Saka, Willian and David Luiz available to him.
West Brom vs Arsenal odds
5/1 West Brom
Odds courtesy of Betfair
West Brom vs Arsenal head-to-head in last five meetings
31 Dec 2017: West Brom 1-1 Arsenal – Premier League
25 Sep 2017: Arsenal 2-0 West Brom – Premier League
18 Mar 2017: West Brom 3-1 Arsenal – Premier League
26 Dec 2016: Arsenal 1-0 West Brom – Premier League
21 Apr 2016: Arsenal 2-0 West Brom – Premier League