The pair were travelling around Scotland looking for antiques that they could auction off for a profit as they went head-to-head in the final round of the competition.
After spending a couple of days rifling through antiques centres and specialist shops, Catherine and Mark met up to discuss their purchases.
The 52-year-old was thrilled with his items, which included a soft toy Poodle, as he proudly showed them off to his co-host.
But he was in for a shock when he saw what Catherine would be taking to auction and for the first time on the show he was left speechless.
Catherine was anxious about showing her items to Mark
Catherine showed her items to Mark who was taken aback
Well, say something then!
Mark was lost for words as he looked over the antiques expert's selection after she noted he would probably be very "nasty" about her items.
But after falling silent for quite a lengthy amount of time, she demanded: "Well, say something then!"
He finally answered: "I'm looking because I like the late Chinese plate with the dragons painted on it," pointing to a decorative plate.
Mark went on to add: "I don't mean to break your heart Catherine but I do rather like your collection."
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Mark confessed that he actually liked some of the items Catherine had found Antiques Roadshow's most unusual finds Mon, April 3, 2017
Antiques Roadshow: The most unique items to be seen on the BBC show.
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Mark admitted that he feared Catherine would win the competition
The pair's amicable appearance comes after they came to blows on yesterday's show when Catherine shoved Mark.
When he made a scathing comment about one of the items she had purchased, she grabbed his arm and pushed him in outrage.
Antiques Road Trip continues on Monday on BBC Two at 5.15pm.