CINCINNATI -- When most starting pitchers are averaging around 96 mph with their fastball in a game, few would do a double take. When Reds top prospect Hunter Greene -- whom many would agree isn't most starting pitchers -- does that, it's downright alarming.

Making his Great American Ball Park debut and third big league start on Friday vs. the Cardinals, Greene didn't give the home crowd what they might have expected. Although he often battled well, it wasn't enough to help the Reds find a win. Cincinnati was handed a 4-2 defeat to extend the club's losing streak to 10 games.

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"I was talking to some of the guys," Greene said. "Obviously, it would have been nice to go longer, but you have more pride in the days where you don't have your best stuff. You just still have to go out and compete. I felt like I did that today, so I was proud of myself for that."

Greene, 22, lasted 3 1/3 innings and was charged with three earned runs on four hits with four walks, three strikeouts and a hit batsman.

"I knew going into the game that it wasn't there, but you can't say, 'Oh guys, today's not a good day, I can't go in and compete.' Nobody wants to hear that," Greene said. "You just fight through and look on the positive side and attack the guys."

Coming off an April 16 start vs. the Dodgers in which his fastball averaged 100.2 mph and he set a record with 39 pitches at 100-plus mph, Greene was nowhere close to that level with his velocity.

• Of his 66 pitches, Greene used his four-seam fastball 42 times. It averaged only 95.8 mph and topped out at 97.2 mph, according to Statcast.

• Of 22 swings on the fastball by Cardinals hitters, five were misses. Last time, at Los Angeles, Greene got 13 whiffs on 28 swings.

• Greene's slider -- used 19 times -- averaged 83.9 mph, down from the average of 87.9 last time.

• In a positive sign, Cardinals hitters didn't square up against Greene. Their average exit velocity was 82.5 mph and maxed at 98.6 mph.

"It wasn’t easy," Reds manager David Bell said. "Right from the beginning, he had to make pitches. Even with the velocity down a little bit, he’s still throwing really hard. Also, it’s not all about velocity. He was still using what he had really effectively, even with his fastball."

Some misfortune burned Greene in the top of the first inning. The first batter, Dylan Carlson, opened with a soft single to left field. The next batter, Paul Goldschmidt, lined a single to left field, where Tommy Pham let the ball bounce under his glove for an error that scored Carlson.

"I think we prepared for [Greene’s high velocity], and then it’s always easier to adjust down than up, right?" Cardinals manager Oliver Marmol said. "So we were prepared for the velocity and his mix of that with the slider, but early on, you could tell the velo was a tick down, and guys made an adjustment."

Greene, who walked two batters over his previous two starts, issued a one-out walk to Nolan Arenado and a two-out walk to Tommy Edman that loaded the bases. But he escaped when Lars Nootbaar looked at a 95 mph fastball for a called strike three.

"I honestly thought he did a great job of just pitching," Reds catcher Aramis Garcia said. "Pitching with what he had, I think that’s going to be a valuable lesson for him."

Other than a four-pitch walk to Carlson with two outs the next inning, Greene worked a clean second. In the third, Arenado hit a one-out single and was left stranded.

Greene, the No. 22-ranked prospect in baseball by MLB Pipeline, could not finish a fourth inning that started with a walk to Nootbaar and Edmundo Sosa getting hit by a pitch. Following a one-out single off first baseman Joey Votto's glove that loaded the bases, Bell lifted the rookie for reliever Jeff Hoffman. Two more runs -- charged to Greene -- crossed on Goldschmidt's single to left field that made it a 3-0 game.

Bell checked on Greene during the game, but his arm's health was not an issue. Fatigue, however, was noticed in the fourth inning.

"You never know -- he could’ve pitched out of it," Bell said. "But once one more reached base, I thought it was time there."

Now an MLB-worst 2-12, the Reds are enduring their longest losing streak since they dropped 11 in a row from May 16-27, 2016.