ENGLEWOOD, Colo. -- Wide receivers Demaryius Thomas and Emmanuel Sanders certainly have been involved in the Denver Broncos' offense this season.

The Broncos would like for them to advance a level beyond that, however.

Thomas has been targeted 30 times and Sanders 34 times in four games. No other player on the roster has more than 16 targets.

But the Broncos' top two receivers have combined for two touchdown receptions in four games -- both by Sanders.

They have received plenty of attention from opposing defenses -- so much so, that even as the Broncos pound away with the league's No. 3 rushing attack at 143 yards per game, those defenses have continued to keep extra players in coverage, essentially deciding they'd rather take their chances against the Broncos' running backs rather than let Broncos quarterback Trevor Siemian pick away at them with Thomas and Sanders in full flight.

Or as coach Vance Joseph has put it: "When you're facing a lot of Cover 2 or shell coverage, No. 88 [Thomas] and No. 10 [Sanders] are really taken out of the ballgame."

Demaryius Thomas is still seeking his first touchdown catch this season. Kyle Emery/Icon Sportswire

That look has opened up things for others. Tight end A.J. Derby had four catches for 75 yards and a touchdown in last Sunday's victory over the Raiders, and Bennie Fowler is tied with Sanders for the team lead in touchdown catches with two.

However, the Broncos' quest to get Thomas and Sanders the ball in the scoring zone will continue.

Thomas has been targeted at least eight times in three of the Broncos' four games and Sanders has been targeted at least eight times in two games, including 15 targets in the team's Week 3 loss in Buffalo. The Raiders, however, got enough pressure up front to disrupt Siemian when he dropped back to throw, and the Broncos leaned on the run game even more.

Thomas and Sanders were each targeted just five times against Oakland, as Sanders had four catches for 27 yards and Thomas had one reception for 11 yards. It was Thomas' first one-reception game since the Broncos' win in Super Bowl 50.

"We're close, I think," Thomas said. "As long as we move the ball and score points, that's what we need to do. [Defenses] have to make choices and these are their choices right now. ... We'll keep working."

Joseph was asked this week if he thought the Broncos' top two receivers were getting frustrated.

"Receivers? They're always frustrated," Joseph said with a laugh. "They want to catch 10 balls a game. I like that. Especially from [Sanders]. I like his personality. He wants the ball every play. That's cool. He should want the ball every play. He's a competitive dude."

"I think the difference is, it happened a little last year, too, but we weren't running it as well as we'd like to," Siemian said. "We want to be difficult to defend regardless of how teams are playing us. ... Guys know they're going to get touches, they're going to get involved. We'll be all right."

Joseph has said he believes the Broncos can continue to do things schematically to get the ball to Thomas and Sanders in red zone situations. But he added that if the Broncos continue to stress defenses with their run game -- they've run for at least 140 yards in three of their games -- it will be far more difficult for those same defenses to keep using an extra defender when Thomas or Sanders or both are in the formation.

"If that happens, we have to continue to run the football and force teams to give us fair coverage," Joseph said. "And when we get fair coverage, we have to take advantage. So far ... our run game has been effective. We have rushed for 140 yards a game, and if we can do that we can control the game."

Asked if he believes defenses will have to consider changing their ways if the Broncos keep pounding the ball, he added: "They will."