Albion have enjoyed a superb start to their Championship season after another summer of change that saw Mason appointed as the head coach.
An opening day victory over Blackburn Rovers was followed up by a 3-2 victory over Wrexham last Saturday.
The victory leaves Albion point top of the Championship table with Pompey on Saturday.
And a victory over the Fratton Park side would put Albion into territory they have not been in for 28 years.
The last time Albion won their first three games of the season came back in the 1997/1998 campaign under Ray Hartford.
An opening day victory over Tranmere Rovers courtesy of goals from Kevin Kilbane and Andy Hunt was followed by a 3-2 win on the road at Crewe with Lee Hughes netting a brace.
And the best of the three victories arrived on August 24 as a Keith Curle own goal handed Albion a 1-0 victory over arch rivals Wolves.
Last week saw them win their first two league games for the first time since 2017 - and a win over Pompey could put Albion top of the Championship table.
Mason has insisted in recent interviews that there is still more work to be done to get Albion to where he wants to be - and the head coach has again been putting his side through their paces ahead of Saturday.
Here is a selection of pictures to come from Albion training this week:
Nat Phillips is put through his paces in West Brom training (Photo by Adam Fradgley/West Bromwich Albion FC via Getty Images)Alex Mowatt sprays a pass. The West Brom man penned a new deal this week (Photo by Adam Fradgley/West Bromwich Albion FC via Getty Images)Ryan Mason and James Morrison alongside the other Albion coaching staff (Photo by Adam Fradgley/West Bromwich Albion FC via Getty Images)Isaac Price looks on during West Brom training (Photo by Adam Fradgley/West Bromwich Albion FC via Getty Images)Krystian Bielik is tracked by Devante Cole in West Brom training this week (Photo by Adam Fradgley/West Bromwich Albion FC via Getty Images)Mikey Johnston during West Brom training. The winger is pushing for a start this weekend (Photo by Adam Fradgley/West Bromwich Albion FC via Getty Images)George Campbell on the ball during a West Brom training session (Photo by Adam Fradgley/West Bromwich Albion FC via Getty Images)Jed Wallace in possession. The captain scored just 28 seconds after coming off the bench at Wrexham (Photo by Adam Fradgley/West Bromwich Albion FC via Getty Images)George Campbell plays a pass in West Brom training (Photo by Adam Fradgley/West Bromwich Albion FC via Getty Images)Cole Deeming and Callum Styles were all smiles (Photo by Adam Fradgley/West Bromwich Albion FC via Getty Images)Thumbs up from Aune Heggebo who has had an impressive start to his Albion career (Photo by Adam Fradgley/West Bromwich Albion FC via Getty Images)Caleb Taylor in West Brom training (Photo by Adam Fradgley/West Bromwich Albion FC via Getty Images)Josh Maja on the ball in training. The West Brom striker has been working his way back to fitness in recent weeks (Photo by Adam Fradgley/West Bromwich Albion FC via Getty Images)Isaac Price in action for West Brom during training (Photo by Adam Fradgley/West Bromwich Albion FC via Getty Images)
