When did they start acknowledging Undertaker's undefeated streak?

[Sadistic]

I doubt from his first Wrestlemania that the plan was for him to remain Undefeated 20 years later. I assume it was coincidental that he kept winning at Wrestlemanias and then someone though "wait, we might be onto something interesting here". I'm wondering whent his happened. When specifically did they start acknowledging that there was an undefeated streak?

[Executioner]

I believe JR mentioned it at WM XIV during his match with Kane, but WWE didnt make it a big deal til X-Seven if i remember correctly

[Xero]

The first time I remember it being prominent was the Flair match, since that was his tenth and he put up 10 fingers to signify it.

[Rammsteinmad]

Yeah I remember it mostly from the Flair match. I think it may have been mentioned at 17, really can't remember tbh, but it definitely became a legit thing at 18.

[Jordan]

WM 11, Vince says that The Undertaker is undefeated at Wrestlemania.

[Savio]

Originally Posted by Xero The first time I remember it being prominent was the Flair match, since that was his tenth and he put up 10 fingers to signify it.

They also had an interview in the program about all the people he beat

[Nicky Fives]

X-8 versus Ric Flair is the first that I remember...... he even held out 10 fingers following his victory.....

[XL]

Originally Posted by Fragile X WM 11, Vince says that The Undertaker is undefeated at Wrestlemania.

Originally Posted by Xero The first time I remember it being prominent was the Flair match, since that was his tenth and he put up 10 fingers to signify it.

These.

Whilst it was mentioned in passing at 11, it didn't become a "Big Deal" til 18.