The home leg, which was watched by 9,0000 fans in Glasgow, saw the Scottish outfit draw 1-1, and they will be allowed to welcome 18,500 supporters to their ground on Saturday.
Following the departure of Neil Lennon during last season, Celtic now begin a new era under the management of Ange Postecoglu, who arrived in the summer after John Kennedy guided the club to the end of the campaign.
He watched the Scottish side kick off their pre-season campaign in impressive fashion, defeating Sheffield Wednesday 3-1 and Charlton 2-1 in their first outings.
Their form would then take a slight dip in two games against Championship opposition, firstly drawing 0-0 with Bristol City before they were defeated 1-0 by Preston North End on home turf.
Postecoglou then took charge of his first competitive game on Tuesday, as they welcomed FC Midtjylland in the first leg of their Champions League Qualifying second-round tie, and winger Liel Abada scored on his debut to put the Bhoys ahead in the first half.
Their task was made tougher on the stroke of half time, though, as Nir Bitton was shown his second yellow card, but their opponents would also be reduced to 10 men early in the second half, only for the Danish side to draw level through Evander in the 66th minute.
They will now play their final pre-season friendly, with the second leg taking place on Wednesday and the Scottish top flight commencing next Saturday.
The Bhoys will aim to build confidence with a positive result heading into a crucial continental game and a decisive domestic season, as they aim to regain the Scottish Premiership trophy after rivals Rangers won the title last year following Celtic's nine consecutive league wins.
West Ham United will also aim to record another pre-season victory to build towards an important Premier League season, after an impressive sixth-placed finish last campaign.
David Moyes's men defied the odds to achieve a top-six finish, earning Europa League football for the upcoming season as a result, and they will aim to again finish well inside the top half again this time around.
The Irons started their pre-season campaign with a training camp in Scotland, followed by a clash with Dundee, with the sides drawing 2-2 as Jamal Baptiste and Jarrod Bowen got on the scoresheet for the London side.
They would then record a 2-1 victory over Northampton Town, thanks to an own goal and a Conor Coventry finish, followed by a goalless draw with Leyton Orient.
In their most recent friendly, the Irons comfortably defeated Championship outfit Reading 3-0, as the scoring was opened with an own goal before Coventry again found the net alongside Ben Johnson.
With a home clash against Atalanta coming up, the London club will aim to continue their strong pre-season form with a victory in Scotland against tough opposition.
Given he will serve a suspension on Wednesday, Nir Bitton should start at centre-back to give relief to Stephen Welsh, who will lead the back line in the second leg.
Albian Ajeti will likely lead the line against his former club, as he continues to try and ignite his career in Scotland following a disappointing spell with the Irons.
West Ham deployed a strong side for the friendly against Reading, and they should continue to field their best players in the run-up to the season to ensure they are prepared.
One absentee is midfielder Declan Rice, who continues to be rested after an impressive campaign with England in Euro 2020, being one of the key men as they reached the final.
Academy graduate Conor Coventry has been a key man in the pre-season campaign so far, scoring two goals in the last three games, and Moyes will continue to assess the talented midfielder.
Celtic possible starting lineup:
Barkas; Ralston, Bitton, Urhoghide, Bolingoli; Shaw, Soro, Forrest; Dembele, Griffiths, Ajeti
West Ham United possible starting lineup:
Randolph; Fredericks, Diop, Dawson, Johnson; Coventry, Noble; Bowen, Fornals, Benrahma; Antonio
We say: Celtic 1-3 West Ham United
West Ham will likely field a more full-strength side than their opponents given Celtic's upcoming continental clash, and that should see them record another victory.
Celtic's focus should understandably be on their trip to Denmark, meaning chances will be given to plenty of squad players.
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