"I've got the chance of a lifetime to push into the top 10 and now I want to keep winning and keep pushing my way up. I'm playing the best darts of my life in terms of results but I've still got an extra 20% of my practice game to bring to the big stage.
"I didn't used to like playing against Mensur but I enjoy it now so I'm looking forward to getting stuck into that game."
He will next meet Mensur Suljovic, who earlier beat Ian White to reach his third World Matchplay quarter-final in four years.
The popular Austrian, who brushed aside Steve Beaton for the first time in his career at the ninth time of asking in round one, looked like he would breeze into the last eight with the minimum of fuss when leading 7-2 - but Diamond fought back bravely.
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White won six of the next eight legs to threaten the kind of comeback that Dave Chisnall pulled off against Michael Smith 24 hours earlier only for Suljovic to find a second wind and get the job done.
The Gentle ended up with an average of 97 compared to White's 93 while he also managed five 180s and an impressive high finish of 121 on the bullseye.
Suljovic may have endured a disappointing - albeit unlucky - Premier League debut earlier this year but since then he's won two PDC titles, including a maiden World Series of Darts crown, and he'll no doubt fancy his chances of landing his second major TV title following last year's Champions League of Darts triumph.
The 46-year-old has never gone beyond the quarter-finals at the Winter Gardens and will next meet either Rob Cross or Darren Webster.
"My performance was not that good, but I am so happy that I won," Suljovic told .
"It was a very hard game, Ian is a good player. There are lots of good players in this tournament who are favourites ahead of me but I will keep trying my best to win."
"The last time I got to the semis here was in 2014 and I actually feel like I'm playing better now than I was then."
His first quarter-final in Blackpool since 2014 will be against Peter Wright, who produced a superb display to defeat Kim Huybrechts 11-5 in the final match of the night.
Both players were averaging over 105 in a superb duel when Snakebite led 5-4 but the 2017 UK Open champion pulled away with five legs on the bounce - all won in 15 legs or fewer and included checkouts of 130, 116 and 90.
The Belgian took the next but it merely delayed the inevitable as Wright wrapped up victory with an average of 105.6 - the highest of the tournament so far - and a checkout percentage of 50%.
"I felt comfortable and I felt focused - I'm happy with how I played," said Wright.
"In my next game it will be tough because Simon is a good friend but when we get up on stage I will have to treat him as the enemy. He is fantastic though and he's playing really good darts at the moment."
Wednesday July 25
Second Round (best of 21 legs)
Thursday July 26 (1900 BST)
Quarter-Finals (Best of 31 legs)
TV Channel: Sky Sports
Friday July 27 (1900 BST)
Quarter-Finals (Best of 31 legs)
TV Channel: Sky Sports
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