Worried about Aljaz's health at the moment and rather thought he would end his season after the last retirement but then having fought so hard to get back to this level after hsi last run of injuries I understand the temptation to chance it and keep going. So far as the opponent, Sock can be good but frequently of late he has been very bad and his attitude has left a lot to be desired so I would not be surprised to see the generally consistent Aljaz come out on top here.
Putting rankings to one side, that is a good win for Dom and Daniell against two strong players. And it looks comfortable as well. The next match also looks winnable on what could be Dom's last event of the season perhaps.
Should also add that Daniell's usual partner, Demoliner, is playing with Sam Querrey this week, in Vienna. Not sure if that is a sign that Daniell and Demoliner are splitting, but he would feel like a good partner for Dom to get if he is available.
Having had injury issues at the end of last year and not added any points after 03/10/16, already in the top 50 he no doubt saw the late season this year as a chance to further push up his ranking. So he's maybe been frustratingly caught between shutting down his season and trying to gain in this 'window'.
Well, he is in good company if he does shut down his season. By trying to play through the injury (which it sounds like he was from Wimbledon onwards) it might make it worse.
Now that is a promising victory for Dom and Marcus! Last 8 would be versus Zimonjic and a local wild card who are playing together, and Mannarino and Paire. I would fancy Dom and Daniell should be able to deal with either of those pairings.