We have more quarter-finals in store at the Australian Open and returning to discuss the men's action is our tennis columnist, Dan Weston...
"In these previous head-to-head matches, Nishikori has really struggled on serve against the Djokovic return game, holding around the 65% mark, and a repeat of these historical issues would give him an absolute mountain to climb to get the win tomorrow morning."
Tsitsipas again triumphing in a tight match
Our first two semi-finalists are now known, with Rafa Nadal easing to a straight-set win over Frances Tiafoe, while Stefanos Tsitsipas edged Roberto Bautista-Agut in a tight four setter. Yet again, Tsitsipas' seeming gift for winning close matches was in evidence, with the Greek player winning just 51% of the points in the match, but still not requiring a fifth set, and also pegging Bautista-Agut back several times when a break down as well.
Tomorrow's second batch of quarter-finals feature two strong favourites - Milos Raonic and Novak Djokovic, who face Lucas Pouille and Kei Nishikori, respectively.
Pouille a big underdog for serve-orientated clash
First up at around 3:30am UK time is the Raonic vs Pouille clash, and of the two matches on the card tomorrow, I anticipate this to be the more serve-orientated. A first-set tiebreak is in the low 30%s, considerably higher than the average match, although not nearly in the bracket of two out and out big servers.
Raonic is 1.182/11 for the win, which looks a little short to me, although not absurdly so, but there does look to be a little value on Pouille. A concern would be the 3-0 head-to-head lead that Raonic enjoys against his French rival, particularly as two of the three matches were in quick conditions - Brisbane (hard court) and Stuttgart (grass).
Pouille with head-to-head defeats in favoured conditions
The reason why this is concerning is that Pouille has a superb record in quick conditions (I have him running at just over 34% ROI from 45 matches at the venues on tour that I have established to be particularly quick-paced, including Brisbane and Stuttgart, since the start of 2016), yet he still hasn't been able to get the better of his Canadian rival in conditions that suit him.
Having said that, Raonic enjoys those conditions too (7% ROI in the same time period) but while I don't anticipate conditions to be as quick as those events today, it would be a worry that if Pouille hasn't been able to threaten Raonic particularly in conditions that really suit him, it's even tougher to think he will tomorrow in more medium-paced conditions.
Perhaps predictably, Pouille's historical match-up issues come on return with Raonic being broken just once in seven head-to-head sets, and it's difficult to see him getting any success tomorrow without being able to win at least several tie breaks.
With this in mind, it seems worthwhile being cautious and I advise no entry here.
Nishikori needing huge serve improvement to shock Djokovic
The second match on Wednesday morning sees Kei Nishikori have the unenviable task of facing Novk Djokovic, with the Japanese man a heavy 8.4015/2 underdog to make the semi-finals.
Djokovic is the 1.132/15 favourite, with my model making him a little bigger at 1.201/5, but this discrepancy isn't big enough at all to be actionable either. Novak has an edge on both serve and return data, and takes a 17-2 head-to-head lead into their encounter as well.
In these previous head-to-head matches, Nishikori has really struggled on serve against the Djokovic return game, holding around the 65% mark, and a repeat of these historical issues would give him an absolute mountain to climb to get the win tomorrow morning.
Against the best returner on tour on hard courts, a repeat of this is extremely likely and I would be very surprised indeed if Djokovic didn't take his place in the semi-finals in several days.
Follow Dan on Twitter @TennisRatings