Steve Johnson beat Sandgren 6-7(5), 6-3, 7-6(3). We all remember who Sandgren is, the guy that Federer beat from a come from behind win. They went into a tie break, but Johnson mostly controlled it. I guess that Sandgren was still feeling the pain on that Federer lost and probably seeing another ghost during his match against Johnson specially in the tie break.
That is what I'm trying to say, he is really good, however, his defeat against Federer may have put a dent on his spirit and it was like a repeat again against Steve Johnson in this tournament. So it might take some time before he can overcome it mentally.
Jason Jung upset Anderson, the champion in 2018. He will be facing Norrie, another tough match for him, Norrie beat wild card Brian Shi.
I agree, I think that when he was in control against Federer and then losing it has taken a lot out of him mentally. We see this all the time in sports and it can take time before he can recover and sometimes they never recover from this so it will be interesting to see how he goes in future tournaments this year.