O’Brien lined up against the 24-year-old at Craven Cottage earlier this year as the Terriers secured an impressive 2-1 victory over Marco Silva’s side in this fixture.
Goals from Danny Ward and Duane Holmes allowed Huddersfield to overcome the threat posed by Fulham in this particular fixture.
Since this clash, the Terriers have managed to secure a place in the play-offs by winning seven of their last 11 league games.
Currently two points adrift of AFC Bournemouth who occupy the second automatic promotion spot, Huddersfield are still in with a chance of overtaking their Championship rivals in the league standings.
However, the Terriers will need some help from elsewhere as the Cherries still have four games left to play this season.
Having sealed a 2-1 win over Barnsley last week, it will be intriguing to see whether Huddersfield will be able to extend their unbeaten run to six games on Saturday when they face Coventry City.
Asked on the latest episode of the Sky Sports EFL Podcast to name the toughest opponent he has faced in the second-tier this season, O’Brien said: “I’d probably say Adarabioyo, the centre-back for Fulham.
“I played up top when we played away, I played in the striker [position].
Quiz: Can you name what club these Huddersfield Town one-appearance wonders play for now?
“Yeah, I couldn’t get anywhere near him.
“He was so quick, so powerful and he just seemed to bypass my whole game and I just felt like I was just running after him the whole game basically, yeah.”
It is hardly a shock that O’Brien has named Adarabioyo as his toughest opponent as the defender has produced a host of impressive performances for Fulham this season.
During the 39 league appearances that he has made for the Cottagers during the current term, Adarabioyo has helped his side keep 14 clean-sheets by averaging a WhoScored match rating of 7.01 in the Championship.
Having demonstrated that he is more than capable of delivering the goods in the second-tier, it will be intriguing to see how the defender will fare in the Premier League next season for Fulham.
As for O’Brien, he will be determined to play a key role for Huddersfield as they aim to secure promotion alongside the Cottagers.
The 23-year-old has made 42 consecutive starts for the Terriers in the Championship and is expected to feature in his side’s meeting with Coventry this weekend.