• Darren Bent misses training with groin problem
• Chris Smalling set to start at right-back against Bulgaria

The England captain, John Terry, second left, is impressed with England's young players.

John Terry has admitted he and the other senior England players are "looking over our shoulders" at the bright young things making waves at clubs such as Manchester United and feels that the older guard all face a genuine challenge to retain places in Fabio Capello's side over the final year of his tenure.

The Italian called up the uncapped Chris Smalling, Phil Jones and Tom Cleverley from the champions for Friday evening's Euro 2012 qualifier against Bulgaria following the trio's eye-catching performances over the first few weeks of the Premier League campaign. Of the three, Smalling is expected to start at right-back, a position in which he was considered a novice a few months ago, with Capello to decide whether Jones or Gary Cahill will partner Terry at the heart of the defence against Lothar Matthäus's team.

Yet, even if the 19-year-old is not handed a debut at the Vasil Levski stadium, the senior members of this England squad are well aware that the national manager now boasts younger options if standards slip. "We all feel that pressure of them pushing us and fighting for places," Terry said. "They firmly believe in themselves as club players and feel they can make this step up. In the long-term that's great for the whole squad, but we're obviously looking over our shoulders.

"They're all very comfortable. The way they've come in and expressed themselves has been great. It's always time to freshen things up and if the younger players are good enough, they're old enough. A lot of these younger guys have benefited from going out on loan – the likes of Danny Welbeck and Daniel Sturridge, too – and have great ability. That's also reassuring for the future."

The emergence of the trio and Danny Welbeck, absent with a hamstring injury, has maintained a trend established with the breakthroughs of Joe Hart, Ashley Young and Jack Wilshere after last year's disappointing World Cup finals, a tournament which thrust the spotlight on to an underachieving generation. While Capello expressed his admiration for Smalling's progress in an unfamiliar right-back berth – "He's improved even in the four games he's played there with United, and is playing with confidence," the head coach said – it is Jones who has made a real impression on Terry.

"He made his debut [for Blackburn] against us, playing very well against Didier Drogba, and we were eager for Chelsea to go and sign him even then," the England captain said of the centre-half who cost United £16.5m this summer. "He's very quick, good in the air, very comfortable on the ball, and he reads it very well as well. He literally has all the attributes that he'll need to become a very good England player.

"And from what I've seen of him this week, he's even come on leaps and bounds from where he was last year. The eagerness to improve is key. He's the one who really sticks out in our position. He's one I'm looking over my shoulder at. He clearly wants a place in the England side, whether that's mine or someone else's. He's hungry for that. But I'm fortunate enough to have the shirt at the moment and it's down to me to keep it regardless of how the other guys are playing.

"The older players are really keen to go and do well in the tournament next summer. Whether this is our last, or the next one is, we're not going to give it up easily. But we also know that if we're not performing for our clubs, the manager won't pick us. There was an example of that this week with Rio [Ferdinand] being left out of the squad, and we all know what a great player he is. But the manager won't take crap from anyone. If you're not playing, it doesn't matter who you are, you won't be picked."

England endured a stuttering end to last season with the 2-2 home draw against Switzerland, a result which sees them top the group on goal difference from Montenegro, with a trip to Podgorica to come in the section's final round of fixtures. Yet there is confidence going into this evening's game against a beleaguered Bulgaria, with England having won their previous 10 fixtures in September, when their players are at their freshest.

Capello, who may prefer Gareth Barry in midfield to Scott Parker but has a major doubt over Darren Bent, who missed training with a groin problem, chose the eve of the game to offer a reminder of his intention to select only personnel who show the necessary "pride" to play.

That was perhaps a reference to the West Bromwich goalkeeper Ben Foster, who had reiterated his desire not to be included in the squad in talks with the general manager Franco Baldini last week. "If you want to stay in the squad, you need to respect me as the manager and respect my choices," Capello said. "But if any player says he's ready to return, then OK, no problem. I never close my door to people because you can make mistakes and understand what you did. My door is never closed."