Hello and welcome to live coverage of the quarter-finals of the Cincinnati Masters. Four fascinating ties coming up today, starting with Juan Martin del Potro of Argentina taking on Jeremy Chardy.

DEL POTRO 6-1 6-3 - MATCH! Chardy's run is over - a timid surrender in the end. Del Potro reached match point with a delicate putaway at the net, but Chardy dug in to bring the score back to deuce. He saves another match point, but after an eight-minute game he finally blasts long, and hands del Potro a place in the semi-finals. Next up for del Potro is the winner of the match between Novak Djokovic and Marin Cilic.

DEL POTRO 6-1 5-3 - The sixth seed seems to ask the umpire whether to review a service called out - that's not how the review system works, is it? Either way, the call of long was correct, and it makes little differnece as del Potro thumps a winner off the second serve, brings up game point with a 95mph winner down the line, and holding with a delightful flat hit. He's just one game away.

DEL POTRO 6-1 4-3 - No nonsense from Chardy here, however - the 25-year-old is a talent, with a strong one-handed forehand and backhand, and when the errors disappear from his game he capitalises with a hold to love.

DEL POTRO 6-1 4-2 - The Argentine cements the break with a hold to love. Hard to see how the Frenchman can get back on terms here - he's been well off the form he showed to beat Andy Murray in the previous round. Suffice to say he must at minimum break del Potro in one of the Argentine's next two service games.

DEL POTRO 6-1 3-2 - BREAK! Chardy back in trouble, with del Potro playing perhaps the point of the match so far, a low backhand approach followed by a volley on the stretch. 0-40 once more, but Chardy crashes a two-handed backhand clean down the line to pull to 30-40, then slaps a forehand across del Potro to force deuce. But this is a miracle escape too far, and a double fault from Chardy seals the break for del Potro.

DEL POTRO 6-1 2-2 - Tidier - much tidier - from the Argentine, who eases into a 40-15 lead. A forehand into the net from del Potro delays the inevitable, but a forehand out wide from Chardy costs the Frenchman the game.

DEL POTRO 6-1 1-2 - Chardy came close to taking the lead in the second set, and having missed three break points, he then offers his opponent the same opportunity at 0-40 down. Remarkably, he too gets back to deuce, finishing with an ace, before reeling off the next two points to hold. So we stay on serve despite huge opportunities for both players.

DEL POTRO 6-1 1-1 - From having been absolutley in contorl behind his own serve, del Potro suddenly finds himself 0-40 down. He finds a way back to deuce, however, courtesy of a drop shot and a rash forehand from Chardy when he had more time available to him. Del Potro has his own opportunities to close it out, missing two game points, but does eventually hold.

DEL POTRO 6-1 0-1 - Having raced into an 40-0 lead, Chardy looks rattled when two forehands miss their mark. But after a stern conversation with himself, he wins the next point with a confident volley. Important to start the second set well if the lucky loser has any intentions of reaching the last four.

DEL POTRO 6-1 - SET! A moment of farce as del Potro reaches 40-15 and Chardy walks off, thinking the set has been lost. Not yet! But with Chardy looking a beaten man, it's no surprise that the next point is an ace for the Argentine. 27 very gentle minutes, and Chardy's heading out in a hurry here.

DEL POTRO 5-1 - BREAK! Chardy just cannot get on top in his service games. For the third time in a row he goes a break point down, and though he saves it the Argentine playing like he believes he just needs to stay solid and the job will be done. Sure enough, he earns another break point, Chardy's groundstrokes are too short, and del Potro volleys his way into a double-break.

DEL POTRO 4-1 - It's a curious situation del Potro finds himself in. His left wrist is a major concern, especially given he spent the best part of a year on the sidelines with problems to the right wrist. But despite having a doctor's appointment next week, he's playing on here, and playing very well indeed. He stretches the lead to 4-1 with a crunching winner flashed across court on the forehand.

DEL POTRO 3-1 - That's a crucial hold for the Frenchman. The game was running away from him already, and he afforded del Potro a break point. Having saved that with a vicious forehand, the world number 38 comes through to get on the scoreboard.

DEL POTRO 3-0 - Another mishit from Chardy - he qualified for the main draw here as a lucky loser, but this is the first time he has played so unconvincingly. The unforced errors mounting up quickly for Chardy as the Argentine holds to 15.

DEL POTRO 2-0 - BREAK! The Olympic bronze medallist doesn't have to do too much except keep the ball in play against his French opponent before racing into a 0-40 lead. Chardy's mishits costing him. Two strong forehands hint at him getting out of trouble, but del Potro comes in on the backhand volley and tucks the ball away. Early lead for the sixth seed.

DEL POTRO 1-0 - Not the tidiest opening point, but del Potro has a booming serve and once he gets behind it, he takes control of the game. Chardy blasts a forehand long to confirm the hold for the Argentine.

Del Potro looked in some trouble during his last 16 match yesterday. He had a wrist problem, but came through somehow to reach this stage. Chardy, by contrast, had the match of his life to beat Olympic champion Andy Murray in straight sets.

This the first time the pair have met on the ATP Tour, so there's no head-to-head record to compare. However, as the sixth seed and a former US Open champion, del Potro comes into the match as favourite.