#2 Brock Lesnar and Drew McIntyre
Brock Lesnar entered the 2020 Royal Rumble at #1, and for the first half of the match, ruled the roost, making as many as 13 eliminations in the match. The Beast eliminated the 13 Superstars that entered the ring after him, but was finally undone by Drew McIntyre, who went on to win the 2020 men's Royal Rumble match.
Following Lesnar's elimination, McIntyre and The Beast had a staredown as the WWE Champion was in disbelief. They then exchanged some words with Lesnar clearly incensed by McIntyre eliminating him and possibly seeking retribution.
McIntyre teased a babyface turn a few weeks ago, and has revealed in recent interviews that WWE have allowed him to be himself, which has shown a different side of him. This possible babyface turn fits in well if he is to feud with Lesnar, who is clearly disliked by the WWE Universe.
This has WrestleMania written all over it, and it's quite certain that McIntyre will announce on the RAW after Royal Rumble that he wants The Beast's WWE Championship at WrestleMania 36.