Unlike in many previous cases this season, the Whitecaps coach can base his decisions Saturday on several options rather than necessity. Rennie has fewer lineup concerns because he does not have to deal with as many injuries as he has in previous weeks, while suspensions and international absences are not factors either.
"It's much better than not having choices," said Rennie after a practice this week. "At certain points in the season, we've just not had the choice of who we can play, but now we've got that, and I think it pushes everybody a little bit higher."
The Whitecaps (10-7-6) are unbeaten in seven of their past 10 games. Rennie has options up front, in midfield and on the back line as they try to break a tie for second place in the Western Conference with the Rapids (9-7-9), who are unbeaten in five games.
Arguably, Rennie's most difficult decision will come on the back line as he determines whether to insert veteran central defender Andy O'Brien, a commanding presence on the pitch, who has been out since early June with a hamstring injury. O'Brien's return could break up an effective partnership between Johnny Leveron and Carlyle Mitchell, who appears the most likely to be moved to the bench.
The duo has filled in admirably while the Caps have coped with injuries to the back line that are easing but still taking their toll with Brad Rusin (ankle) and captain Jay DeMerit (torn Achilles) out.
"It's nice for us to have a little bit of competition, because we haven't had that," said Rennie. "For many weeks, we didn't even have a centre back on the bench. So it's nice to have to make a decision on who starts, and that will be a difficult decision."
Striker Darren Mattocks' return from a knee injury that required surgery last month also means that Rennie can rest Kenny Miller, who scored a goal in Scotland's friendly against England in London on Wednesday and has travelled across the Atlantic twice this week.
Whatever he decides, Rennie can be confident that replacements will be up for the task.
"Obviously, we're still just building our team and I think that we want to be improving all the time," he said. "But we've scored more goals this year than we've scored in the whole of last year (and 2011), and there's still a third of the season, so that's a positive sign. ... But we're also making saves at the other end, and defending well and starting to possess the ball better. So we've got a lot to build on.
"But the last few games don't matter so much. It's just about this next one."
Coaches in all sports love internal competition, and Rennie is no exception. While the Whitecaps are much more stable than they were a year ago, when a series of mid-season roster changes led to a summer swoon in the standings, the competition for jobs is much higher.
"When I first arrived, there was a lot of building to be done of the team," he said. "There was a lot of adjustments that we had to make. There was a number of players that probably weren't quite at the level that we thought. But I think the squad's getting stronger. It needs to just keep improving.
"But I think you saw when we played Portland away we were missing six or seven key players, and the guys who came in did really well (as the team earned a draw.) So the squad's much deeper than it was before, and there's more competition than there was before, and that's what we want."
Mattocks said he felt burdened to carry the team offensively last season, but Camilo and Miller, who both scored in a 2-0 win over the San Jose Earthquakes last week, have lightened his load in a difficult season.
DeMerit said the battle for jobs is much different than it was when he arrived on the scene with Vancouver's 2011 expansion club. But in order to succeed as a team, players must accept the increased competition and expectations.
Midfield still remains somewhat of a question mark. Gershon Koffie, who played a holding midfielder role against San Jose for the first time and performed well, is expected to play the same role in Denver.
So the engine-room crew is not expected to change much in Denver. But Rennie has the comfort of knowing that he can make revisions if he wants to.
Notes: Rapids midfielder Hendry Thomas is eligible to return after serving a two-game suspension. ... New Colorado designated player Gabriel Torres, a member of Panama's national team, could make his debut. ... The Whitecaps won two of three meetings with Colorado last season while the other game ended in a draw.