Southern Brave were 21 for 2 when the match was halted due to rain against Welsh Fire, who had scored 181 for 5 in their innings with Wells contributing 53 and Phillips adding 48. The match ultimately ended in a no-result due to the weather conditions.
Southern Brave secured their place in The Hundred Eliminator at the Kia Oval on Saturday thanks to rain intervening at Utilita Bowl against an already-eliminated Welsh Fire.
The Brave came into the match knowing that a point would guarantee their presence in Saturday's showdown but at the halfway stage, with 181 posted by the Fire, they would have feared losing control of their destiny.
Two quick wickets - Alex Davies for a duck and then James Vince for 19 - further set the Brave back. But on the stroke of Vince's dismissal, with rain falling steadily, the umpires took the players off.
The rain never abated, and with just 16 balls having been bowled of the Brave's innings - a minimum of 25 balls are required to deliver a result - the game was duly abandoned.
It was a bitter pill for the Fire to swallow. With the bat they were irrepressible, with Luke Wells and Glenn Phillips especially destructive, sharing a 76-run partnership from just 30 balls to propel the Fire to their highest-ever score in the tournament's history.
Wells, registering just his second fifty in the competition, took just 28 balls to reach the milestone, while Phillips was spectacular, clubbing five sixes - including one hit over square-leg against Jofra Archer that sailed 102 metres - from just 19 balls. In all, 10 sixes were struck across the Fire's innings.
For the Brave, only Akeal Hosein escaped punishment, the West Indian left-armer conceding just 21 from his 20-ball quota.
Ultimately, it was immaterial. Brave are through to face either Northern Superchargers or Birmingham Phoenix, with the latter's game against Manchester Originals tomorrow determining the final placings at the top.
Brave skipper, James Vince, said: "Bowling first, things probably got away from us a bit. We were sloppy. Some good players got going and we weren't able to shut them down, so it was always going to be a tough ask to chase that down.
"We had a few messages saying the weather might be on its way so it we had a few discussions about how to approach those first 25 balls; thankfully the rain came just in time.
"On the whole, across the tournament, the bowling group gets a lot of credit. They're quality, experienced bowlers. Our batting goes under the radar a bit. We'd like a few more guys in form, but on the whole we've been reasonably consistent."