Mills, 22, arrived in Hove after joining the club from Essex over the winter. The left-armer is believed by some to be the fastest bowler in England, with Surrey???s Stuart Meaker and Middlesex???s Steve Finn his main competitors.
Mills, who only started playing cricket at the age of 14, came to prominence ahead of the 2013-14 Ashes series when he was used as a net bowler for the England squad to help prepare them to face Mitchell Johnson.
He has however suffered from injuries, and played just six Championship games for Essex last season. His potential is not in doubt ??? Essex veteran James Foster says Mills is the fastest bowler he has ever kept to.
And Robinson told Sky Sports News HQ that when he saw an opportunity to sign Mills, he did not hesitate.
???He didn???t want to go really,??? he said. ???He had an injury problem which was a bit of a concern from Essex???s point of view and they couldn???t come to an agreement (on a new contract). We were alerted and managed to sign him.
???It???s obviously a little bit of a gamble because he???s got an injury record. But he???s done fantastically well for us. He???s fighting fit at the moment. He???s bowling absolute rockets. He’s as quick as anybody in the world.
???From his point of view it is consistency, and staying on the pitch, but if he can keep himself fit and keep himself right he has got to be knocking on the [England] door soon.
???He???s quick. Anybody who is quick makes them a handful, and then you chuck in the angle [of the left-armer]??????
Luke Wright, newly appointed as Sussex???s one-day captain, has been impressed with Mills in the nets.
???It???s a bit of a nightmare actually because when you sign someone like that you have to face them more often ??? I???ve got a few bruises on my stomach from facing him yesterday in the nets,??? he said.
???It???s nice to get to the main games now so he can hit the opposition instead of us. He???s very exciting ??? we???ve seen him before when he was bowling at the England team. He was marked out then as someone for the future.
???He???s got himself really fit and I can see him in an England jersey at some point. He???s exciting and hopefully he can put in some big performances.
???As soon as you???ve got pace you???ve always got a massive chance, you almost get fast-forwarded to the top level. That???s what the England selectors are always looking for. We got on the wrong side of Mitchell Johnson all last winter. We???ve seen how destructive he can be.
???Hopefully Mills can be that person, first for Sussex, but then for England in the future. He???s still young, he???s still learning the game. We don???t want to put too much pressure on him too early. But he???s certainly a very, very exciting prospect.???